Set in Scotland as a large activist group who wants to rid the waters of the UK’s nuclear warheads is gaining steam, a fishing boat sinks and the crew drowns, possibly due to the passing of a submarine carrying such warheads, the HMS Vigil. At the same time, one for he sailors aboard the British sub, Chief Petty Officer Craig Burke (Martin Compston) dies of a supposed drug overdose. Detective Chief Amy Silva (Suranne Jones) and her partner (and once and future girlfriend) Detective Sergeant Kirsten Longacre (Rose Leslie) investigate the situation separately on both land and sea, but they’re communication is limited to coded emails because the sub’s location needs to stay secret. At least we get to see a steamy, sapphic make out sesh between the hotties first!