In 1977, a gravely ill 19-month-old Qatari girl was flown to a London hospital, where her condition continued to worsen, baffling her doctors.

On the sixth day, the observing nurse was startled to see that the girl began to lose her hair. She realized that the patient’s symptoms were strikingly similar to those in Agatha Christie’s novel The Pale Horse, which she had been reading.

In Christie’s novel, the murder victims had been killed by thallium poisoning. Tests confirmed elevated levels of thallium in the girl’s urine, and doctors treated her accordingly. Three weeks later she was well enough to go home.