Leys Physical Training College was famous for its excellent discipline and Miss Lucy Pym was pleased and flattered to be invited to give a psychology lecture there. But she had to admit that the health and vibrant beauty of the students made her feel just a little inadequate. Then there was a nasty accident - and suddenly Miss Pym was forced to apply her agile intellect to the unpleasant fact that among all those impressively healthy bodies someone had a very sick mind...