After Alice (Abigail Hardingham) returns to her family home, the Websters struggle to deal with the trauma she has suffered.
As Matthew (Jake Davies) is faced with an unbearable request, Gemma's (Keeley Hawes) suspicions about what happened to her daughter begin to grow. The Royal Military Police (RMP) and the German police agree to share jurisdiction over the case and launch a manhunt for the second missing girl. During a search of the disused bunker Alice escaped from, Julien (Tcheky Karyo) discovers a key clue that points the investigation towards a local suspect.
In 2016, war journalist Stefan Andersson (Olafur Darri Olafsson) is helping Julien make his way to Azwya, across an active war zone. What is Julien doing out in Iraq? And will he make it home unscathed? Meanwhile, back in Eckhausen, Gemma and Sam (David Morrissey) continue to drift apart, while RMP Staff Sergeant Eve Stone (Laura Fraser) has to deal with her father.