Michael Swanwick's Periodic Table of Science Fiction

Thallium

204.383

A Perfect Murder

Agatha Christie knew she'd been poisoned as soon as the symptoms began to

show. Give her that much credit, at least!

Hair loss, lethargy, tingling of the hands and feet, slurred speech ? It

was thallium poisoning. Thallium mimicked potassium, an essential

element, which made it particularly difficult to get rid of. The body

would excrete it into the intestines where, insidiously enough, it would

be mistaken for potassium and reabsorbed.

There was no known cure.

Agatha knew, too, who the murderer was. Subtract ten days from the onset

of hair loss, and one arrived at a literary luncheon. One accepted a cup

of tea from a writer of international renown who was nevertheless jealous

of her sales. Oh yes, Ernest was the culprit, all right.

But that wasn't important now. Agatha needed to find a cure, and quickly.

If there was no known cure, she would simply have to find an unknown one.

Oddly enough, this was not her first brush with thallium poisoning. As a

child, several classmates had come down with it?and one had died?after

drinking milk from a cow that had eaten molasses baits laced with

thallium sulfate and laid out for the rats. Seven children had drunk the

milk, yet only six had fallen ill. One had not. What was his name?

Gummy! Gummy Oglethorpe. The other children had called him Gummy because ?

Agatha lurched to her writing desk and snatched up the bottle of blue

ink. Spasmodically, she drank it down.

The next day she was a little better, and the day after better yet. She

kept drinking ink until the symptoms were entirely gone.

Gummy Oglethorpe had been a compulsive fountain pen sucker. It had turned

his gums the most amazing blue. Clearly something in the ink?she

suspected the Prussian Blue?had substituted potassium for thallium,

allowing the latter to be flushed from his system.

Now that she was better, Agatha turned her attention to her would-be

murderer. Bloody amateur. She needed a way to kill him that would be

swift, sure, and so perfectly undetectable that she would never be

suspected of the deed.

She found it, of course. Give her that much credit, at least!

The End