- Writers: Chris Chibnall
- Stars: Adam Wilson , Andrew Buchan , Arthur Darvill , Benji Yapp , Carolyn Pickles , Charlotte Beaumont , Charlotte Rampling , David Tennant , Eve Myles , Hollie Burgess , James D'Arcy , Jodie Whittaker , Joe Sims , Jonathan Bailey , Marianne Jean-Baptiste , Matthew Gravelle , Meera Syal , Olivia Colman , Oskar McNamara , Pauline Quirke , Peter De Jersey , Phoebe Waller-Bridge , Simone McAullay , Steve Bennett , Susan Brown , Tanya Franks , Vicky McClure , Will Mellor , William Andrews
More clues come to light - cigarette butts found near the body and the fact that the burnt-out boat belonged to Ellie's ex- brother-in-law who left his wife Lucy, Olly's mother in debt when he left town. At the same time Tom, Ellie's son, meets Susan Wright, who offers to let him walk her dog. Beth threatens Becca over her affair with Mark and is restrained by Paul. She tells Mark she does not want his baby but later they reconcile over family photos. Jack Marshall comes under increasing suspicion as Karen tutors Olly - with whom she has sex - into writing a piece on the newsagent for her paper. Chloe is convinced of Jack's guilt after boyfriend Dean says Jack was always touching the sea scout boys but Jack later admits to the police and to Mark that his previous conviction was for having sex with a young girl, whom he later married. They had a son who died in a car crash aged six and the boys he hugged are substitutes for his dead son. Not everybody is convinced and a hate campaign against Jack develops.