Leo Bruce's brilliantly ingenious new detective story opens with an extract from a diary: notes made by someone planning the perfect, the ideal murder — the one which no police, no detective, could solve. The murderer's gratification will be entirely cerebral, his (or her) triumph being one of mind over matter.

Up to a point it would seem that nothing could be better planned: the place a remote shelter on the promenade at Selby-on-Sea, the occasion a blustery evening in late November, the victim almost ready-made for a crack of doom from a small coal-hammer. . . .

But this is not the first murderer whose plans are upset by an unexpected coincidence and in particular by the unpredictable mind of Carolus Deene, that unique schoolmaster-detective.