The investigation continues to take unexpected turns, with Nikki managing to get behind the mask of the lead suspect. Jack has a breakthrough at the festival site and Nikki takes a dangerous opportunity. A surprise event at the Lyell brings some hope.

The Lyell team return to the crime scene as another victim is in peril. Family ties are tested to their limits as they reveal the dark secrets that led to the tunnel collapse, and Jack is put in a difficult position when a blast from the past comes to visit.