Suicide must be investigated. Especially when a Royal Navy sailor kills himself on a nuclear submarine, only days after his wife's brutal murder. Now Lieutenant Danielle Lewis, the Navy's finest Special Branch investigator, must interrogate the tight-knit, male crew of HMS Tenacity to determine if there's a link. Isolated, and standing alone in the face of extreme hostility, Dan soon realises that she may have to choose between the truth and her own survival. Justice must be served, but with a possible killer on board the pressure is rising and her time is running out. Tense, dramatic, claustrophobic and brilliant, this is Headline's crime launch for 2015.