One cold spring morning in County Cork, two fishermen find a bundle of rags floating in the Blackwater River.

It is the mutilated corpse of a retired music teacher. His hands and feet are bound, and his neck bears the mark of a garrotting wire. The Garda want to wrap this case up before the press get hold of it. But when a second man is found murdered, the body bearing all the same marks as the first, it looks like the hallmark of a serial killer...