Editor's note: We are pleased to present the forth and final episode of an original story about an unusual laboratory relationship. (Use the navigation tool above to catch up.)

I am making some procedural notes for tomorrow's experiment in my laboratory notebook when the lights suddenly go out. The hissing from the ventilation system fizzles, cloaking the lab in an otherworldly silence. All I can hear is my own breathing.

I look out the window to my left. The tall brick buildings across the street are dark as well. Above the roofs of the city, the dim gray sheen of a cloudy night sky stretches indefinitely.

I hear Nancy's footsteps come across the hall and see the silhouette of her broad shoulders in the doorway. "The offices are closed," she says, getting right down to business. "We'd better take care of everything."

I nod without a word, get up and follow her into the laboratory. There is an eerie lack of noise. Only the light fixture on the far left, by the entrance, is lit by emergency power. Its illumination barely reaches the corners of the lab. Already, the still air seems to be thickening.

Nancy pauses beside the slumbering fume hood and rubs her square chin with her fingertips, gazing down in thought. "Let's do the minus seventy, then come back to the lab."

"Get the fume hood first," I advise, pointing behind her. When the fume hood is off, the chemicals stored inside can drift out into the lab.

"Ah, right," Nancy says, turning away to shut the hood. I watch her go on her tiptoes and lean down on the handle with her weight until the sash clacks into place.

Nancy heads out of the lab and I follow her down the long, still corridor. Only every third light in the hallway is on emergency power, and so the pale sea green walls appear unusually dark. There is no one around except Nancy and me, no sound aside from that we make. I watch her sturdy ankles above her chestnut leather loafers, the tense fabric of her long denim dress as it shifts with a jerky sway to the rhythm of her stride.

After passing two doors on the right, Nancy opens the third and says to me, "Prop the door open. I'll unplug the freezer."

I find a wooden doorstop on the floor while Nancy walks to the long waist-high freezer at the end of the narrow room and tugs the cumbersome unit away from the wall. I shove the doorstop under the door and go to join her. Nancy is behind the freezer, bending down to remove the plug. I cannot resist admiring the curve of her darkened torso.

"Got it," Nancy says, standing. "I'll push; you pull. You know where to bring it?"

"The autoclave room's the only one with an emergency plug, right?"

"Uh huh."

Nancy braces her back against the wall and shoves the freezer away with all her might. We roll the unwieldy unit across the room with little effort but it can barely angle through the door frame, and so we have to maneuver it back and forth several times before we can ease it outside. Once in the hallway, we wheel it toward the autoclave room with a loud, gravely grating that echoes in the long, empty corridor. At the entrance to the autoclave room, we have to ease it back and forth again before we can angle it through the doorway. Finally, we wheel it into the darkened room. Only one light is working under emergency power, at the far right corner of the room. I lead the freezer past the central island, which houses two massive autoclave machines, and into the lit area.

"There's the plug," I say, pointing to two outlets mounted onto a low beam that extends from the autoclave island across to the far wall. The outlets are designed for a three-pronged plug of an unusual shape: each of the three prongs is a short plane tangent to an imaginary central circle, with one of the planes thicker than the others, creating an asymmetric plug. One of the sockets is already occupied by a freezer standing against the island, but the other is free.

"Let's slide it right next to that other freezer," I say.

"Is the socket free?" Nancy's view is blocked by the autoclave island.

I tell her it is, and so we maneuver our freezer with some difficulty to fit between the one already there and the ice machine against the opposite wall. We push the freezers right up against each other to leave a narrow path between them and the ice machine. Nancy hands me the plug, and I lift it toward the outlet to try and plug it in. But the plug won't fit. Not because of the metal prongs themselves, but because the rubber casings of the two plugs can't fit into the outlets at the same time. Rather than coming from the back face of the plugs, the wires emanate from their sides, a design that causes the wire of the plug that's already in the outlet to block another plug from being inserted beside it.

"Crap," I say, lifting my arms to try again. "These aren't going to fit." I try to force it, but the other plug's casing keeps it from fully inserting.

"Let me try," Nancy says. "They have to fit in together. We had an outage a couple of years ago and it worked then." She comes over and takes the plug from me.

"This freezer wasn't here then," I point out.

"That would explain it," Nancy says without missing a beat. She raises her right arm toward the outlet, but finds she cannot reach. She then tries to lift her right leg to climb onto the freezer, but puts it down again in frustration when the stiff denim of her dress restrains it. "Damn; I can't even climb up here." She hands me the plug to hold, then bends over to undo some of her skirt's buttons. Starting at the bottom, she undoes five, so that the skirt opens above her knees, then climbs onto the freezer and reaches up to push the plug in. Unsuccessful, she withdraws it and, holding the prongs below the socket for a moment to study the arrangement. She lowers the plug and rolls her sleeves up to her elbows, exposing the tight, freckled skin of her muscular arms. "I know we can do this," she says. "Can you get me some packing tape?" I leave without a word to get the tape. My gentle footsteps echo in the corridor. I find the tape and a pair of scissors in the lab and return to the autoclave room, where Nancy is on her knees on top of the freezer, relaxing with her head down and her eyes closed. She doesn't move at first. I fantasize a touch – just a touch of her short cinnamon hair. But Nancy will soon open her eyes and see me staring at her. "Nancy?"

She opens her eyes and lifts her head without a blink. "Got it?" she asks. I hand her the tape and scissors, and she places them beside her on the freezer. "I think we can push each of the plugs halfway in and then tape them to hold them in place," she says. "What do you think?" "Try it," I shrug. "What can we lose?" Nancy reaches up and tries to position the plugs together in the socket. The top two buttons of her collar are undone, permitting the lightly bleached denim to bulge away from her chest and create an open space. The only illumination comes from behind her, so there is nothing but a dark gap inside.

"I think I got it," Nancy finally says, absorbed in her work. "Do they both have power?"

I look down. "The red lights are on," I confirm.

"All right. Now I just have to tape these in place."

The tape makes a loud tearing sound as Nancy wraps it around both plugs and the metal support beam. After securing them, she cuts the tape and sticks the end down. "That should do it," she says, putting the tape and scissors down. "Let's hope it holds." She leans forward and turns on her knees to climb down, exposing to me an even wider gap at her chest, yet the space remains dark, impenetrable. She throws her legs off the freezer and sits down, then braces herself with her arms to slide off. Once her feet are on the floor, Nancy stands erect and rubs the dust off her hands. The fabric of the dress now rests flush against her chest. The slight curvature of her breasts can barely be inferred beneath the stiff denim. The air in the autoclave room is still, the only sound that of Nancy's grainy alto voice as she says, "Now let's get the lab in order."

I rotate the desk's lampshade on its wire support. Its metal frame scrapes gently against the harp. On the wall above the lamp, there is a vertical oval of rolling shadow. The light is most intense at the bottom, near the shade. The top of the oval opens and disperses into darkness near the ceiling.

I allow the shade to slow, and the clockwise rotation in the oval begins to take the form of a deformed bicycle wheel. It is a geometry possible only in a world of shadows: the wheel is oval and always widest at the top. Its spokes are cones, diffuse at the hub and narrowing to a blunt point at the wheel's edge. I let the movement stop, and when the shade comes to a halt, a faint conical spoke comes to rest at the very bottom of the oval, pointing directly down.

A white piece of paper sits before me. I have written a letter, but I don't know if I will send it:

Dear Nancy,

I knew something like this was going to happen eventually. I was driving myself crazy pretending I didn't feel anything for you, pretending we could just be colleagues.

It's over for me, Nancy. I don't care about the stupid diatoms. I don't care about the lab. Maybe you can deal with me strictly on a professional level, but I can't deal with you that way. I'm sorry, but I can't handle seeing you every day and pretending I don't feel anything.

I just don't know what to tell Angie. I don't even know if I'll ever see her again. I'll bet she called you tonight. I wonder what you told her.

Maybe I'm being childish. I start the lampshade spinning again, pondering the oval wheel with its faltering shadows. I let the shade come to rest again after a while and turn the lamp off, plunging the room into darkness. I get up to go sit on the bed, sending the shimmying bedsprings into fresh squeals of protest. When they finally settle down, all I can hear is my own breathing.

I have to make some decision soon. My time is running out. If I go back to Angie now, I'll probably be able to work things out with her. But I can't wait much longer.

Nancy leads the way back into the lab. The lightly bleached denim fabric of her dress shifts stiffly with the movement of her legs. Back inside the lab, she stretches both arms in front of her with a flourish. "Now what?" she asks, resting her hands on her hips and glancing around with a playful frown. She is directly under the one working light. "Actually, there's not that much to do," I answer. "It'll only take a few minutes." Nancy takes a deep breath and continues to look around the room while she gathers her thoughts. I study her right eye, the closer to me, its black pupil fixed in sea green crystal. "So what's there to do?" she asks, and counts the tasks on her left hand as she names them: "Put the incubator on emergency power, the refrigerator on emergency power...anything else?" "I'm not sure what's in the hood, but we should double-check that nothing's open, even if the sash is closed." "Well, you do the fume hood. I'll get the extension cords."

"Sounds good." I watch Nancy walk into the shadows on the other side of the central lab bench. I don't know what's coming over me. I'm so excited to be alone with her like this. I try to stay collected. I open the fume hood, cap an open bottle and then push the handle down until the door shuts with a bang.

"Take it easy," Nancy says as she passes the fume hood with coils of thick orange cord bundled in her arms and a flashlight in her hand. "You're gonna shatter the glass." She walks over to the refrigerator beside the entrance to my office and drops the cords into a loose pile on the floor. They look like long, tangled orange snakes. Nancy strokes her chin with her left hand. "Where's the emergency power?"

"If I remember correctly," I say, walking toward her, "there's only one emergency outlet in the lab, behind the computer bench."

"O.K.," Nancy says, distracted. "You hold the flashlight; I'll unplug the fridge."

She offers me the flashlight, and I take it and switch it on as Nancy steps to the back of the refrigerator. She bends down and grips the side of it with her right hand, leaning behind the unit and groping for the plug with her left. Her body is balanced on her left knee while her other knee is up, resting against the side of the refrigerator. I cast the flashlight beam directly past her right shoulder. The small gold hoop in her ear gleams with the light. "Why don't we move it away from the wall?" I offer, even though I am enjoying watching her struggle. "It's too heavy," she says, short of breath. "I'll have it in a minute, anyway." With a jerk, she removes the plug from its socket. She then stands, pulling the cord out with her. She brushes her dress off with one hand, holding the plug out to me with the other.

A passion is running through me, an urge to just grab her and kiss her. I don't know what she'd do.

"You want to hook that up to the extension cord?" she asks impatiently, pushing the end of the cord toward me to bring me out of my reverie. "I'm coated with dust." I set the flashlight down, take the cord from her outstretched arm, then attach the plug to one of the extension cords in the tangle on the floor. As the metal prongs slide into the socket, Nancy notices the left arm of her dress; the white inner face of the rolled-up fabric is smeared with a brown streak. "Shit," she says, trying unsuccessfully to brush it away.

The denim sags above Nancy's belt, having gathered there when she was reaching for the plug. She tugs the material down from her thighs, pulling it below her belt to straighten it. I untangle the cords as she does this, making a trivial comment that the cords should have been untangled before we plugged in the refrigerator. Nancy watches me in silence once she has straightened her dress, her eyes unfocused. I wonder what she's thinking. Could she be feeling the same thing I am? Suddenly, Nancy sneezes – a delicate, transparent sneeze. "Oh no," she says with a buzzy voice, "this dust..." She sneezes again, holding her hand to her face as she turns to go get a tissue from her office. I unplug both computers from the outlet beneath the computer desk, then insert the extension cord plug into the left socket. I can hear Nancy blowing her noise. She comes back out of her office just as I finish and stand up. "Just a little allergic reaction," she says, approaching the computer desk. Her wide shoulders are exaggerated by the shoulder pads beneath her dress. "Do you have anything growing in the incubator?" "Nope." "Me neither," she says. She turns around, goes to the incubator, and opens the door. The right side of the chamber is blocked from my view by her figure, but the left half is empty. "Nothing?" I ask. "She's got two carboys in here," Nancy says, referring to the graduate student. "Should we save them?" "We might as well while we're here," I say, relishing my time in Nancy's presence.

"You want to bring the flashlight over?" I retrieve the flashlight. Nancy lowers to her right knee and leans against the door frame of her office, with the side of her head against the wall as she reaches behind the massive incubator. I switch the flashlight on and shine it past her. The gold hoop in her left ear gleams in the light. "I can't reach," she says.

"Should I try?" "No; let me shift my position a little. Just move the flashlight for a second." Once I pull the flashlight back, Nancy leans farther forward and wedges her chest into the space between the wall and the incubator, causing her collar to be pulled wide by the incubator's metal edge. When I lower the flashlight once more, its beam bleeds light onto the pale, lightly freckled skin of her chest.

I don't know what it is that's pushing me over – perhaps the lack of sound, the otherworldly feeling of isolation. Just me and Nancy, outside time, outside space. My heart is racing. "I've got hold of it," she says. "Now I just have to pull it out." I transfer the flashlight to my right hand and raise it above Nancy's head so that the beam is angled down. Then I can't resist: I place my left hand on Nancy's left shoulder – just a casual contact. Her foam shoulder pad compresses under my gentle pressure. Nancy's body twitches intermittently as she tugs at the plug. "This is a hard one," she says. "I can't get the damn thing out." My hand closes tighter on her shoulder. Her body twitches again. "Just hold the beam steady," she says, tugging once more. "I've almost got it." Another tug. My heart refuses to calm down. It feels like it's about to burst.

Her body jiggles under my hand as the plug comes loose. She backs out from behind the incubator, my left hand still resting on her shoulder. When her upper body is free, I finally let it go. Nancy stands and looks up at me as she turns. The cord still dangles in her right hand. Her dress is gathered above her belt once more, and now dirt is smeared over the right side of her chest. Her collar is pulled wide, and the thin white bra strap that runs over her shoulder is exposed. She is about to say something trivial about accomplishing her task, but then she sees the expression on my face and stops. "Nancy." My hand reaches out and draws gently along her soft cheek, my fingers delicately curled. Nancy lets the cord fall to the ground. She lifts her hands and takes mine in hers, pressing it against her cheek. Her hardened expression has melted; I haven't seen her look at me like this for years. I lift my other hand, quivering, to the slope of her solid neck, my thumb touching her jawbone. I draw it down her neck's soft dry skin, then stop when my little finger touches the elastic shoulder strap of her bra. Nancy stares and presses my hand closer against her cheek. "My god. I didn't know," she says. "I can't help it," I answer, my voice jittery with nerves. Nancy gazes at me, her eyes glazing over. She opens my hand and kisses my palm gently. I can feel her warm breath.

"I've never gotten over you, Nancy."

She presses my hand to her cheek again, then lets it softly fall. She turns away and walks into her office without looking back. I watch her go behind her desk, stoop down and remove her briefcase from a drawer. She averts her eyes as she comes back toward the entrance, grabs an overcoat from behind the door and tosses it over her arm. "You can shut everything down," she says somewhat sadly as she passes, looking past me into the lab. She then heads briskly toward the exit. "Nancy..." I call after her. Her steps stop suddenly before the door, but she doesn't turn around. Her head drops and her right hand rises to cover her eyes. In the clumsy silence, neither of us says anything. Abruptly, she grabs the door handle, snaps it down and yanks it, slipping outside before the door has even fully opened. As the massive gray door creeps shut again, its hydraulic spring emits a passive hiss until, after several seconds, it finally settles into its frame with a loud, resonant click. The room becomes silent once more. The warm air, dense and still, seems to thicken by the moment without her presence.

I picture the kitchen like this. The only light comes through the window, from the moon and the street lamps outside. The wide window ledge supports seven red clay pots, each displaying a different species of cactus with its own unique shape and pattern of intimidating spikes. The cactus barrels appear only as black featureless shapes. To the right stands the refrigerator with its glossy white surface. Gray fruit- and vegetable-shaped magnets hold a school lunch menu and several crayon drawings to the door. At the far wall is the electric stove, with its metal shield gently reflecting light from the window.

To the left, four chairs with their lathed wooden poles and carved back supports are empty. The table's white Formica surface glows a dim bluish gray. Other than the silver napkin holder and salt and pepper shakers near the wall, the table is bare.

Save for the faint sound of my own breathing, the room is silent. I don't think I can deal with this.

I take a deep breath to try to calm myself, then lift the receiver and dial. I can hear my own breathing through the earpiece as I wait for the soft ringing tones to begin. The first one comes, then another before the last is interrupted by a click. "Hello?" answers a woman's slurred voice. She waits for a response, then repeats, "Hello?" "Angie," I finally say, my voice cracking, "it's me." "God, it's late," she says, still groggy. "I thought it was another prank phone call. What time is it?" "About two-thirty."

"I've been asleep for hours. Where are you?"

"We had some problems at the lab. The power went out." "Yeah; I called Nancy when I couldn't get through to you. She said she had to leave you to take care of things alone." Angie yawns before continuing, "I didn't think you'd take this long, though." "There were problems with the core equipment," I say, relieved. "I was the only one around."

"Nancy felt bad about leaving you with all the work." "Well, I'm finished. I should be home soon." "Good. I won't be waiting up, though. Come in quietly."

"No problem."

"See you in the morning."

"See you in the morning," I echo. I hear a loud click, then only gentle background static, barely discernible. I hang up.

The bedsprings squeal with relief as their burden is lifted. I walk toward the exit and snatch my raincoat from the hook. When I open the door, the cool breeze pushes in to assault the room's musty air. The cloudy night sky reflects the orange glow of the distant city.