Perez and the rest of his team are determined to track down the person that helped Michael Thompson's killer. The closer the team get to the truth however, the more dangerous it gets for all involved.

Perez and the team discover that the person that they believed to be responsible for the murders is closer to home than any of them thought. A new light is shone on the murder of Michael when the team discovers who assaulted Kelly. Leanne is struggling to deal with the emotional aftermath after being shot. Perez is troubled when he discovers that Michael's witness protection handler Asha was in Lerwick on the same day that the email was sent out. The team dig deeper into Asha's past and discover a connection to one of McCall's team.