As Calder and Tosh wrestle with the revelation of Annie's past, Noah offers a cryptic clue about the night she was killed.

Standing in Rossi's abandoned hotel room, Tosh and Calder realise that he's been conducting his own investigation into who killed Annie and Bergen. Their fears are verified when MI5 agent Rob Harding warns them that if Rossi is seeking justice for his former protégé, it will be fatal. As they put the pieces of the investigation together, the detectives uncover a failed MI5 operation in London which surprisingly leads them to a local family, as a chilling showdown unravels.

At the kirk, Alan organizes a memorial for Annie. However, the mood quickly sours when an unwanted face arrives to pay their respects, unsettling the family.

In the aftermath of the confrontation, Tosh and Calder interview Rossi, who gives them his reasoning and motivation for going after Annie's killer – a tale full of guilt and revenge.