Originally published in 1946.

Leys Physical Training College is famous for its excellent discipline and its spectacularly athletic students. Miss Lucy Pym, expert psychologist, is pleased and flattered to be invited to lecture there - even if the Olympian splendour of the students leaves her feeling just a little inadequate.

But a nasty accident spoils the occasion, and suddenly Miss Pym must turn her intellect to the unpleasant suspicion that, among all these healthy young students, there lurks an incurably sick mind...