The Tunnel

British and French detectives are brought together when a body is discovered inside the Channel Tunnel.

The killer releases a video stating that the killings are the first of five truths. Karl investigates Gemma's disappearance and the killer's second truth is revealed.

Police in Britain and France race against time to identify and capture the serial killer as he steps up his campaign, targeting an elderly war veteran in his moral crusade.

In France, Karl and Elise battle to locate an elderly soldier before he freezes to death at the hands of the killer. Meanwhile, in the UK, runaway teen Sophie puts her trust in Benji.

The killer's third truth begins as Benji carries out his Samurai mission. The police hope to use teenage runaway Sophie to help trap the killer.

As the killer's incendiary fourth truth begins, Karl and Elise's suspicions fall on Stephen Beaumont and a manhunt begins.

Police think they may finally have a lead as the serial killer's actions escalate in his fifth and final truth, inciting mob violence in England and France.

French police capture but then lose the prime suspect before Elise mysteriously disappears. As Karl searches Danny's flat, things start to fall into place.

Events take a nasty turn for Karl as police get within a hair's breadth of catching the killer.

Karl falls apart when the killer's change of direction becomes too much to bear.