When does Vigil return?

The first series stars Suranne Jones, Rose Leslie, Shaun Evans, Paterson Joseph, Gary Lewis and Martin Compston. Detective Chief Inspector Amy Silva of Police Scotland is sent to HMS Vigil, a nuclear-powered Vanguard-class ballistic missile submarine, to investigate a death on board. Her investigations bring the police into conflict with the Royal Navy and MI5, the British Security Service. The BBC denied that the drama was inspired by or based on a specific real-life event.