Editor’s note: We are pleased to present the final episode of a four-part story about the adventures of a very special scientist-for-hire.

You think you know someone. You work with him, go to the bar, play tennis with him, get inside his head, understand him. But you can never know another man. There are always secrets, always things he’s not telling you, maybe even things he doesn’t know himself.

I thought I knew Mr Big. I knew his name, where his office was, where his kid went to school, what his pet dog was called.

‘Walter’, actually. One of those little dachshund things, looked like some lowlife had cut its legs off. Used to ‘yip!’ on frosty mornings and cobblestones.

Yes, I thought I knew Mr Big. But as I crept along the corridor I realized he was a closed book to me. One of those small books with even smaller writing, probably written in Italian – or German.

I was ready for a fight, and I knew I was going to get it. I kicked open Mr Big’s door, and it slammed back in my face. I pushed against it with my shoulder, ripping the hinges away from the wall. As I fell into the room a sixth sense made me duck, and I heard a click and a whoosh as his Gilson went off. The tip ricocheted and hit the light bulb. I dived to the floor in a shower of glass. Everything went dark. I heard Big breathing in the corner.

“I thought you’d come, Dr Richardsh.”

Click.

I scrambled across the floor to the desk.

Whoosh.

Something stuck into the floor behind me. His aim was good, but I was faster. I reached in my lab-coat pocket for my piece. Damn! – it had fallen out. I felt for it on the floor, in the remains of the broken light bulb. All I got for my trouble was splinters.

“Shit shtill, damn you!”

“I know what you’ve been up to, Mr Big. I have detailed files.”

“You’re good, Richardsh. I knew that when I hired you. But are you good enough?”

I stuck my hand back into my pocket, searching for something, anything. Luckily I found a book of matches. My fingers curled around it, pulled off a single match.

“You can’t hide forever, Richardsh.”

Click.

I put out my other hand and found a leg. It was attached to the desk. I braced myself against it.

“I don’t have to.”

I struck the match and flicked it across the room. I heard Mr Big swivel in his chair, imagined his Gilson swinging around, following the light. I pushed up, tipping the desk over. I caught a glimpse of the matchlight flickering in his good eye, the Gilson pointing the wrong way, a stack of papers fluttering to the floor.

Big stood up, dropping his piece and bringing up a squash racquet. I hit him with a left hook, ducking as the racquet came round. He staggered back and I jabbed, once, twice.

“Give it up, Big. I’ve got the weight, the agility, and three manuscripts in PNAS.”

“You don’t get it, do you? How dishappointing.” He swung the racquet again, and everything went dark: the match had gone out.

I jumped back, the draught from the racquet on my face. I charged forward, pushing Big against the wall and winding him. I punched him in the jaw and he dropped to the ground.

“It’s over, Big. The authorities can deal with this.” I dragged him by the collar into the corridor. His breathing was fast and shallow.

“You think you’ve won, Richardsh.”

I thought I had.

He knew I thought I had. I knew he knew I thought I had. I knew that, but suddenly I wasn’t sure. An icy hand gripped my heart, a cold, icy hand with popsicle fingers. Then I realized what had been bugging me, the little niggle of a suspicion of doubt, the squishiness that lets you know you’ve trodden in something nasty and spread it all over the carpet.

I let go of his collar and stood back, breathing heavily.

“Who’s ‘we’, Big? It’s not just you, is it? I knew you enjoyed Wagner, but I hadn’t realized you had no sense of humour.”

There was a low, rasping sound: Big was trying to laugh.

“Sho you gueshed? Thish phony acshent didn’t put you off the trail? You are good, Richardsh.”

“I’ve suspected for a while, Herr Dick. Why do you keep the accent?”

He shrugged. “Habit. Can’t get rid of it now. Do you know what itsh like, every day, to live a lie, to shit in thish offish – that’sh a nashty cough you have there, Richardsh – waiting for opportunity, marking theshees, dreaming up world-classh projectsh?”

“What did you do with Bruce?”

Big turned to face the wall and said, “He’s in a better place.”

“What? Scunthorpe?”

It no longer mattered. I realized that Big was trying to tell me something that did matter, something bigger than a single PI, bigger than a lab: maybe even bigger than the MRC.

“So, you’re with the Germans. Working with them, one of them. What’s the dirt?”

“Haven’t you notished? They – we are in every lab. All over the world, working, obsherving, organishing. Not dishtracted by shillinesh.” His voice dropped. I helped him pick it up and he said, “We do it better. We dishcover the Unknown Continent, and you play with pebblesh on the shore. Schience needsh ush.”

I was disappointed. I had respected Big, and now he was telling me that he was just like every B-movie scientist that had ever existed, with dumb robot and beautiful daughter. The only things missing were the maniacal laughter and the fluffy white cat. I walked over to the splintered remains of his office door, knelt in the debris, and found my piece. I idly slipped the safety off and gestured with the barrel.

“There’s one thing I don’t understand. Why did you give me the cloning lab?”

“I wanted more like you, Richardsh. You’ve got drive, ambition, gutsh. What we want. What we need.”

“Two things. Why did you steal the proteins?”

“What elshe could I do? You were too shucceshful. You had become a threat. We couldn’t allow you to clone the Japaneshe. That wash evil.”

“I see. Quis custodiet ipsos custodes?”

“‘Who shtirs the cushtard?’ What?”

I leaned against the wall. It had been a long day, and it looked like it was going to get longer. The pain behind my eyes had brought some friends, and they were fumbling in the desk of my mind for the keys to the liquor cabinet. They slammed the drawers shut and looked at me accusingly. Just one shot, and it would all go away. It wouldn’t matter any more. But Mr Big was still here, and the whisky bottle was two floors down.

“What now, Big? I can’t leave you here, I can’t let you continue.”

He grunted, and struggled to his feet.

“Do you know who runsh the MRC, Dr Richardsh? Really? Not me, not Jennie in the offish, not even that creepy guy in Shtoresh who knowsh where everything ish.”

“And not the Germans?”

Mr Big gasped for breath and pulled my ear towards him. I had no choice but to get up and follow it. He leaned over, as if to whisper in my ear.

Click.

Suddenly he shuddered, and fell to his knees. Over his shoulder I caught a glimpse of a shadowy figure at the end of the corridor. I ran to the stairs and took aim – but there was no one there; just fading footsteps, the rain on the windows and the unmistakable odour of a recently fired Gilson.

Big coughed. I was kneeling at his side in an instant, supporting his shoulders. “Come on, Dick. Hold on, it’s not over yet.”

“It ish for me, Richardsh. I’m shorry. I wanted to make it work, make the MRC great again. It’sh – it’sh up to you now: make it shomething to be proud of. Watch” – he coughed again, a rattle in his throat – “watch your back, Nick Richardsh.”

His head lolled in my lap, the spark of life finally snuffed out. And all the books of matches in the world would not re-light it.

I run the show now.

Everyone in my lab is hand-picked, each a brilliant investigator in their own right. They all have stories, and maybe, if you’re lucky, you’ll get to hear them.

There’s not much else to say. It’s a hard life, a lonely life. All I can offer is your own set of Gilsons and shares in a whisky bottle.

And a state-of-the-art cloning facility.

Welcome to the MRC. Don’t let us down.