The case takes an unexpected turn when another young boy goes missing in Chalons Du Bois. Tony, Emily and Mark return to the town in the hope that this might shed light on what happened to Oliver.
Julien and Jorn's investigation leads them further into the murky underbelly of Eckhausen, and the secrets of its conflicting German and British communities.
It is now 2015 and Julien's health is failing, but his determination to track down the missing girl means he has not finished with the Webster case just yet.
Secrets from the past are uncovered as Julien finally learns the truth behind Alice and Sophie's abduction. But time is running out, and nobody in Eckhausen will listen to him.
Julien returns to Paris to visit the father of Sophie Giroux, but Remy isn't all that pleased to see him. When another trauma hits the Webster family, it looks set to tear them apart for good.
Alice Webster, abducted when she was a child, comes back to her family. Detective Julien Baptiste thinks Alice's return may hold the key to the disappearance of another missing girl.
After Alice returns to her family home, the Websters struggle to deal with the trauma she has suffered. Gemma's suspicions about what happened to her daughter begin to grow.
Tony and Julien retrace their steps in Paris as they try and find out the whereabouts of a man who they believe to be intrinsically linked to Oliver's disappearance
Julien is intent on re-investigating the links between a dead witness and Oliver's disappearance. Meanwhile, the stress of re-opening the case starts to take a toll on Emily and Mark's relationship.
While Tony continues on his mission to uncover the truth about what exactly happened to his son, both Emily and Detective Baptiste have to deal with problems in their own lives.
When Tony and Emily Hughes travel to France with their 5-year-old son Oliver, their family holiday turns into a nightmare when Oliver disappears into the crowd of a busy French street.