A prominent French politician is found dead on the border between the U.K. and France, and two agents have to work together on behalf of their respective countries to find the murderer.
Cast: Stephen Dillane, Clémence Poésy, Cédric Vieira, Angel Coulby, Thibault de Montalembert, William Ash, Juliette Navis, Karol Steele, Sigrid Bouaziz, Jack Lowden, Tobi Bakare, Thibaut Evrard, Fanny Leurent, Johan Heldenbergh, Stanley Townsend, Tom Bateman, Laura de Boer, Phil Hodges
Karl and Elise face a showdown with the Pied Piper, while the truth about the Moreau abduction is finally revealed.
Karl makes a forbidding discovery at Elise's apartment, and the pattern of missing people continues.
As a young mother-to-be helps Karl and Elise with their enquiries a new development threatens to tear the pair's partnership apart.
The investigation takes a bizarre and troubling turn when Winnie is sent a box containing a live rat with a set of co-ordinates leading to the latest victim of the Pied Piper.
As Karl and Elise continue their investigation a shocking discovery is made at an immigration removal centre, alongside a sinister animation that contains a hidden message.
Karl Roebuck and Elise Wasserman renew their Anglo-French alliance when they investigate a dark crime that takes place on the murky waters of the Channel as a burning fishing boat turns into a new case for them.