When a young man disappears on the Aberdeen to Shetland ferry crossing and a small boy ends up in intensive care, DI Jimmy Perez and his team investigate, becoming convinced the two events are connected.

DI Jimmy Perez is convinced that Michael Maguire is somehow implicated in the death of Robbie Morton. But with the investigation seemingly under threat before it's even started, he faces an uphill battle to uncover the truth behind Maguire's silence.

The murder investigation takes Perez and Tosh to Glasgow as they try to uncover the reasons behind Maguire's brutal death and his connection to Robbie Morton. But old ghosts return to haunt Perez as his enemies try to prevent him from getting to the truth.