When a woman is found brutally murdered, evidence discovered at the scene links the murder to a 20-year-old unsolved crime. Detectives and old flames Molly McGee and Alex O’Connell are reunited after a long absence to solve the crime.

Devastated by Daisy’s death, Molly discovers a mysterious symbol that ignites her desire to track down Freddie. Alex makes a traumatic visit to Jenny McGinty’s mother, Eileen.

Molly’s daughter Lily partakes in some risqué online activity, which Freddie manipulates in an act of revenge against Molly. Meanwhile, Molly’s suspicions about Freddie’s involvement in Dorothy Moxley’s murder deepen.

Molly hears of Jacinta Clunes’s untimely death and is convinced Gareth is behind the accident. Alex’s interest in the convict bible he found at Dorothy Moxley’s house deepens.

The investigation has a break-through when a woman called Marianne Gowdie is discovered to have the same blood disorder as Dorothy Moxley. A strange night with Gareth causes Alex to recall memories he’s suppressed for years.

Blood samples found on Councillor Jacinta Clunes’s car reveal a familial link to Dorothy Moxley. Alex brings Inspector Lewis to Grace’s house to show him the bones he discovered and learns that Lewis knows more than he’s letting on.

The investigation comes to a head as Gareth takes Molly hostage at knifepoint and Alex is captured by William and the Crofters.