The Tower

DS Sarah Collins and her colleague, DC Steve Bradshaw, investigate the deaths of long-serving police officer, PC Hadley Matthews, and a 15-year-old Libyan refugee, Farah Mehenni.

With Lizzie still on the run, Sarah finally persuades her boss, DCI Tim Bailie, to go public about Lizzie's disappearance.

Lizzie decides to turn herself in, but first she meets Kieran Shaw in secret, who tries to persuade her not to implicate herself.

DS Sarah Collins joins Homicide Command and is tasked with a cold case, and PC Lizzie Adams's willingness to do things by the book is tested by a call-out.

Sarah and Lizzie find themselves working the same murder with their mutual distrust still apparent, but they must cooperate if they are to find a lost child.

The team are left reeling when Brannon's YouTube video goes viral, and Sarah and Elaine make a grim discovery that exposes a vile predator and a vital clue.