Six Four, Episode 1

A compelling premiere. A journalist approaches DC Chris O'Neill about a cold case involving a missing girl. His own daughter is also missing, and his wife goes to London to search for her.

Pauline Wallace receives a ransom call. Chris discovers a link between Annabel's kidnapping and the supposed cover-up in the Julie Mackie case, and Michelle confronts Piers.

An unexpected visitor confronts Chris with the consequences of Michelle's secrets. A visit to Gary McLean's killer brings Chris closer to the truth, and Annabel faces her captor.

A suspenseful finale. Michelle returns to Scotland and accompanies Chris in search of Annabel. Robert and Mackie face off as the truth behind Julie Mackie's disappearance threatens to come out.