A year after surviving a brutal attack, former detective Huw has retreated to a remote coastal home with his wife Alice, determined to leave the past behind. Meanwhile, their daughter Margot is preparing to move in with her boyfriend Sam, but their fragile peace is disrupted when letters begin arriving from imprisoned serial killer Patrick.

Huw uncovers evidence suggesting Jonathan may never have been murdered at all - that Patrick fabricated the confession in response to police inquiries. However, Huw doesn't reveal this, and as Jenny grows suspicious of Huw's intentions, he quietly manoeuvres to have her removed from the operation. Margot begs Huw to stop, but he refuses.