When two seemingly unrelated events - the disappearance of a trawler and a death aboard a nuclear submarine - bring the police into direct conflict with the Navy & British security services, DCI Amy Silva is tasked with heading an investigation both on land and at sea.
S1 E1: Episode 1
When a crew member is found dead on Trident nuclear submarine HMS Vigil, Detective Amy Silva is flown onboard to investigate.
S1 E2: Episode 2
With Vigil in danger, Amy must fight to continue her investigation. Meanwhile Kirsten's enquiries lead to tragedy.
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S1 E3: Episode 3
Kirsten's investigation takes her into the heart of Scottish politics, but when she unearths a Navy cover-up, it leaves Amy questioning who she can trust.
S1 E4: Episode 4
Kirsten closes in on the killer, but their capture reveals the grave threat that Vigil faces. On the submarine, Amy makes a terrifying discovery.
S1 E5: Episode 5
Vigil is forced into lockdown as disaster strikes. With communication lost, Kirsten desperately hunts for clues to the source of the threat to Vigil.
S1 E6: Episode 6
Amy is trapped and running out of time. Vigil's crew must identify the traitor or risk tragedy.