S03E04: Piece of My Heart - Part 2.
As Banks finds himself raking over bad memories for those involved, DI Morton finds herself suspicious of Barber's father Jack, who was the investigating officer in the Gaunt case, and who extracted a confession from Martin Hareford. However, when the files reveal the confession has disappeared, DI Morton suspects that Jack has more to do with his son's death than he is letting on.