Detective Inspector C. D. Sloan knew there would be trouble when he was called in to the student sit-in at Calleshire University. The dons were nervous, the students excited – a clash of some kind seemed inevitable. But what did happen was totally unexpected. First was a most peculiar theft from a dormitory room and then the discovery of a man found clutching at one of the columns of the Tarsus cloister – bleeding slowly to death and able with his parting breath only to utter one enigmatic phrase? To solve the mystery of the cloister murder, Sloan's only clues are the dying man's words. But what significance can 'Twenty-six minutes' really have?