The plot follows detectives Karl Roebuck and Elise Wasserman working together to find a serial killer who left the upper-half body of a French politician and the lower-half of a British prostitute in the Channel Tunnel, at the midpoint between France and the UK. They later learn that the killer—who comes to be nicknamed the "Truth Terrorist"—is on a moral crusade to highlight many social problems, terrorising both countries in the process

Stephen Dillane
Karl Roebuck

Clémence Poésy
Élise Wassermann

Thibault de Montalembert
Olivier Pujol

Cédric Vieira
Phillipe Viot

Angel Coulby
Laura Roebuck

William Ash
Boleslaw 'BB' Borowski

Tobi Bakare
Chucks Akinade

Joseph Mawle
Stephen Beaumont

Tom Bateman
Danny Hillier
A stolen fishing boat found adrift and on fire in the English channel turns into a new case for Karl and Elise. Together and apart, they are forced to grapple with decisions they have made and must make decisions that cut to the deadly heart of the matter: what is the value of a single life?