Trish returns to the scene of the crime - will she remember anything more about the attack? DC Katie Harford discovers a strong lead - a new suspect who doesn't have an alibi. Questioned by Ellie and Hardy, Cath reveals interesting new information about the night of her party. Finally, a breakthrough - Hardy and Ellie get a match on the male DNA found on Trish. An unknown woman walks into the police station. Interviewed by Ellie and Hardy, she delivers some devastating new information.