In 1977, Brigadier Lethbridge-Stewart suffered a shock so great that he was hospitalised. Not that he can remember what happened. Teachers found him, knocked out cold beside the obelisk on the hill. No signs of an attack. No bumps on his head, and no memory of why he lay where he fell, who he'd been with, and great chunks of his past torn from his mind.

It wasn't like any form of amnesia described in the textbooks. The clinic discharged him back to Brendon Public School and he resumed his duties as a teacher of mathematics and rugger.

Two years later and a series of nightmares send him back to the clinic. Then come the pranks played by identical twins, his own erratic behaviour and short-term memory loss leading to a breach of the Official Secrets Act. Someone else is living in his house, driving his car, and making changes to the school he loves.

It seems that the demons haunting him prove too big for him to fight on his own.