After a preserved female body is discovered buried in a peat moor in Sheffield, DI Sonia Hardwick turns to an archaeologist called Professor Patrick Cain for help. Nikki discovers knife wounds to the hands which the professor believes may indicate a ritual killing as the autopsy on the body is carried out. Further wounds discovered around the abdomen and genitalia suggest though that it could of been a sexually motivated attack. Leo ends up searching through his archives for a case he dealt with in Sheffield in 1985 that were committed by self-confessed serial killer Karl Bentley. As he examines the body himself he is caught by Nikki and Leo tells him he thinks the body could belong to a woman called Jodie Fisher who went missing at the time. When Leo pays a visit to Sheffield he is haunted by memories of his own past which put a strain on his relationship with Janet. Another girls ends up being killed on the streets of Sheffield.