He also reads a comic book account of an event in which the Dutch Resistance killed a whole German army camp in the occupied Netherlands during the Second World War by poisoning their water supply with thallium.

He kills two of his workmates by poisoning their tea with thallium stolen from the laboratory, and makes many others ill. For months, the source of the "bug" afflicting the workers at the factory remains a mystery until one unforeseen event leads to Graham's being found out.

As a hygiene measure, all the personalised teacups are replaced with uniform ones, leaving Graham unable to poison people selectively.

He wrote, "Benjamin Ross, who directed and co-wrote with Jeff Rawle, somehow finds the right tone for this material; the events in the movie are dismaying, but the effect is darkly comic.

Not long ago...I observed that anything can be made funny, 'but humor depends on tone, timing and even on taste, and when a comedy starts on the wrong foot, it is hard to regain balance'...The Young Poisoner's Handbook is both funny and creepy, like an accident that is tragic and absurd at the same time (I am reminded of the famous Second City sketch in which mourners at a funeral discover that their friend drowned in a large can of pork and beans).