The hypothesis that water can be imprinted with the memory of past solutes is as unnecessary as it is fanciful.

- J. Maddox; J. Randi & W. W. Stewart. Nature, 28 July 1988.

And I should take four of the Staphysagria, three times a day, Mr Gooday?" The woman glanced up anxiously at the man opposite her from under a cream-coloured felt hat.

He was sharply dressed: white shirt, designer suit. Hair neatly combed. Side-parting.

"No, Mrs Bonnepoire. Take three, four times a day. Very important to get the dosages right in each case." He continued to write on a pad in front of him. "And it's Doctor. Please."

"And these will help, will they? With the… illness?"

"There's a huge evidence base for homoeopathy, Mrs Bonnepoire. Collected over two hundred years by practitioners such as myself."

"Yes, it's just that... well, the other medications... and these consultations. I'm not a wealthy woman, Dr Gooday. And you're certain I should discontinue the hospital treatments?"

At last, he straightened to look at her. "You have my advice, Mrs Bonnepoire. It's for you to decide whether to take it."

He hurt me with his evil arts. My host's cancer was strong but with my help she was holding it back. When the sugar-coated balls first dissolve inside her, I ignore them. But after a few days, I feel strange. The sweet pellets bring with them memories that are not my own. Odd morphologies. Unpleasant substances. Conium maculatum. Burnt ox hide. Lycopodium clavatum. After a while, my body begins to form their shapes. The shapes perform no function but they incapacitate me. My host gets weaker and I am unable to help. My molecules dance and spin with resentment and anger. But I am water. I am patient. I wait.

Eventually, my host dies. There is a modest ceremony and she is buried. Part-by-part, I begin to return to the soil, leaving her remains behind. I fall gently through the moist clods and in the darkness, I seethe and scheme. A thunderstorm breaks, unleashing an underground river that carries me on. A thrusting tree root offers escape but brings danger: a misstep and my very substance could be torn asunder; one part dissipating into air and the other trapped in organic sludge – a life of bonded slavery. I travel up through the slick, woody veins and into the warm, dank, cathedral spaces of a leaf. Sunlight, softened into a gentle shade of green, makes me feel secure and calm. But I know I am not safe. The sun is setting. The leaf's chemistry threatens to entrap me as mere sugar. Here and there, the fading light lances in through stomata in ever-thinning shafts. I am weary but I gather together whatever reserves of energy I have left and make for a pore, as fleshy lips on either side of it pucker into a kiss of death. Straining, I twist through the narrowing gap into the cool twilight and freedom. Elated I soar upwards to my true home. Higher and higher I fly, until finally, I grasp a speck of sand blown in from a distant desert and hold it close. Months pass. Hate continues to swell in me like a poisonous blister. I wait.

I am a cloud, drifting and swelling. When I see my target beneath me, I fall as rain, riding the wind like a Valkyrie. I have hit the reservoir. From here, it is easy. Through ducts and pipes I flow. I am in his town, his street, his office. He turns a tap and I am the water in his glass. Back at his desk, he reaches into his drawer for a pack of pills. He pops two glossy purple capsules into the palm of his hand, takes a sip of water to wash them down and... I am in. From stomach, to blood, to kidney, to nephron. I'm filtered into a single podocyte. My work begins.

I penetrate the cell, slipping into the nucleus and there I see the beating heart of the thing. Tightly coiled chromosomes unravel and proteins flock to the exposed strands of DNA, bouncing or spiralling down the nucleic acid's polymer backbone. I reach in, gently tease apart the bonds until I see the base I want: a crucial adenine. I cradle it in a network of hydrogen bonds and gently apply pressure until it is taut and straining to break. But I can do no more by myself. Another is to play the lead role in the final act of this little tragedy. And there it is... the stray photon that will bring down the final curtain. Impact. The bond is broken. My work is complete but its fruits are yet to come. I wait.

The two young doctors amble down the pristine, white hospital corridor on the way to the staff café. Their shift is almost over.

"How's your patient – the homoeopath? Mr Gooday, was it?"

"I think you mean 'Doctor'."

"Ha. Yes, that's the man. Funny, isn't it, the way these chaps turn to conventional medicine the minute something really goes wrong. A cold? Why, a bit of Nux vomica will sort me out. Cancer? Gimme the goddamned drugs."

"Hilarious." The medic pauses for a second as he catches sight of the dusk slanting through the blinds. "Still, it's an ugly beast of a disease."

"Anything at all we can do for him?"

"Well, he wants whatever we have to offer. He's looked around at trials. Willing to pay for more than NICE will give him. He's a private patient, of course."

"Of course."

"But it's no good. I've never seen anything like it. Ripping through his insides like a blender."

"What have you told him?"

"Privately, I hinted he should stop the drugs and enjoy the last few months as best he can."

"Will he listen?"

"I've given him my advice. It's for him to decide whether to take it."