Shelly Mohan, a housewife and mother of three, makes an irreparable decision and commits a horrific act when Charlie Lynch, a man from her troubled past, contacts her.
After realizing that she may have left evidence in Charlie's hotel room, Shelly concocts a scheme to destroy it at the police station.
When Lynch's true identity is uncovered, DSI Crichett in London reopens a 20-year-old cold case linked to Shelly and Charlie that has political implications.
The investigation builds steam in both countries as Jason's partner, Fiona, grows suspicious of Shelly; the reasons why Shelly changed her identity emerge.
Shelly outmaneuvers the fingerprint test, but a new witness appears who gives a description of a suspect that may point to her.