Perez and Tosh head to Glasgow to try and uncover the reasons behind Maguire's death and how he was connected to Robbie. Old ghosts haunt Perez, however and soon stop him from finding out the truth.

Perez continues his investigation into the murders of Robbie and Michael, but struggles with what has happened to Tosh. He soon however discovers the shocking identity of who Thompson was about to testify against.