Hathaway has been promoted to Inspector after an extended break from the force, and Lewis is enjoying retired life until he's asked to team up with his old colleague again.

When a classics scholar is stabbed to death and dumped in the Oxford Canal, Lewis, Hathaway and Maddox find themselves sorely tested by a bizarre case.

Lewis' reputation is jeopardized when the very first case that he solved as a DI is reopened for appeal and new murders are committed with the original weapon.