DI Chambers and her partner DS Dhillon investigate an elusive serial killer named Gideon Shepherd.

Lucy and Isaac start a new chapter – but their short-lived peace is thwarted by the revival of a police investigation that threatens to expose her double-life.

Lucy desperately tries to cover her tracks as secrets and lies are forced into the open and a terrible deadline looms.

Lucy confronts the reality of her situation and is forced to make an impossible choice. Boyd is tested to her limits in her pursuit of the truth, and Dhillon comes to a realisation, with catastrophic results.