When a landscape artist witnesses a body plummeting from a train speeding over the Sankey Viaduct into the canal below, Inspector Robert Colbeck and Sergeant Victor Leeming face their most complex case. They are unable to identify the disfigured corpse and press appeals bring forward no information, but observing his clothes have a Continental cut, they travel to France where a new railway is being built by a British contractor. Anti-British feeling is rife, and Colbeck and Leeming must put their own lives in danger to pick up the murderer's trail. Has Colbeck finally met his match?