After a failed and bloody mission in Lituania, Fourth Echelon agent Zinnia McKenna must find her way out of the country and ask for the help of a retired agent : Sam Fisher.

Sam and McKenna are hiding in Echelon's safe house while the latter is recovering from her wounds. But Displace is on their tracks and time is running out.

When their location is compromised, the agents must hit the road and hunt for any clue left by Lukas. At Echelon's HQ, Grim and Jo are looking for a reliable IT expert to put them back on track.

While Diana struggle to find a proper work-life balance with Charlie, and McKenna has a hard time dealing with grief, Sam must face the ghosts of his own past.

Echelon must infiltrate a crowded fundraiser to get their hands on Diana's phone. But since Sam mustn't be seen and recognized, McKenna has to take the lead. With the help of Thunder, it's time for a team effort.

With McKenna in extreme danger, Fisher ignores orders and goes rogue. Meanwhile, Diana and Charlie struggle to mask their mutual contempt.

Fisher and Diana lay their cards on the table. McKenna gets back in the game. Grim and Jo face a hard deadline - and a growing sense of dread.

To put a hold on Diana and Charlie deadly plan, the agents board the Lazarev to stop it before it's too late. But as always with the Shetlands, there's more than meets the eye.