The Gordian Knot:

DI Molly Stone returns to work after her ordeal in Jacob’s Ladder and – together with her partner Tony Read – must solve the case of a crucified priest. Cole Randall is now a private investigator and agrees to look into the disappearance of a husband and wife from the Blackwall Tunnel. For both of them, matters are complicated when an old case of a convicted rapist and murderer is reviewed by the Criminal Cases Review Commission (CCRC), and Randall catches Jacob Hansen in Molly's flat. But . . . nothing is what it seems, and sometimes you have to do what is wrong to make things right.