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 might have left crucial evidence in Charlie's hotel room, Shelly devises a plan to destroy it discreetly at the police station.

After Lynch's true identity is revealed, a twenty-year-old case tied to Shelly and Charlie with political implications is reopened by DSI Crichett in London.

As the investigation gains momentum in both nations, Fiona becomes wary of Shelly, Jason's partner.