In a German town, long ago, lives a toothpuller's boy called Klaus. It isn't Klaus's fault that he sees his master steal a diamond from the mouth of a dead man in Frau Drecht's lodging house, or that Frau Drecht and her murderous son want it for themselves.

He has nothing to do with the Jesuit priest and his Aztec companion who turn up out of the blue looking for it, or the Professor of Anatomy who takes such a strange interest in it. No, Klaus doesn't want any trouble.

But when he finds himself with the diamond in his pocket, things really can't get much worse - that is, until the feathered man appears. Then they become a matter of life . . . and death.