The blood-stained clothes of Simon Belgrade are found in Epping Forest, where he disappeared five years earlier whilst out for a run. Frank Miles, Simon's father-in-law and employer, has a history of violence and his daughter Becky, who was heavily pregnant with Simon's child when he disappeared, seems scared of him. She does not want to believe her husband is dead and nor do his mother Eliza and brother Tim, who portray Simon and Becky as the ideal couple. However Simon's friend Dom and his ex-wife Lois tell the team that Simon and Lois were having an affair, as were Dom and Becky. Simon also had a string of failed businesses behind him and was blackmailing Frank over tax evasion, but with no money taken from his account and no passport it seems unlikely that he skipped the country. An examination of a film showing Dom and Simon's childhood haunts in the forest leads to discovering Simon's fate whilst Dan helps Sandra cope with the anniversary of her father's death.

The discrediting of DI Hennessy as corrupt throws into a new light some of his more high profile arrests, including that of crooked businessman Edward Monroe, jailed for killing oncologist Dr Caldwell, whom he blames for the death of his daughter. For Sasha, now alone after discovering her husband's infidelity, the case is painful as she has always believed Monroe murdered her former colleague DC Tyler. As fresh interviews are conducted, it turns out that Caldwell was not a pleasant man and had made enemies of his colleague, Dr Hallerman, passed over for honours; Daniella Yates, director of a cancer charity who was having an affair with Caldwell; and Caldwell's duped wife. However a statement from Grace, a hotel employee of Monroe, throws a more humane light upon the convicted killer, as well as giving Sasha some closure for Tyler's death. Steve, meanwhile finds himself billeting his son Stewie, who has run away from home.

Elderly dementia sufferer Nancy leaves her care home to report that her policeman husband Jimmy, who disappeared in 1956 was actually murdered. Harry Page, an old friend of the couple, reports that Jimmy had gambling debts and got into a fight the night that he died. Sasha takes Nancy back to her old house where she recalls Jimmy's violence and jealousy. A grim secret is discovered in the bedroom wall, in turn leading to the solution of the murder. Meanwhile Steve is called to the police station when his son Stewie is cautioned for minor drug possession, which brings him into conflict with his ex-wife Tricia. They do not part on good terms.