Tenacity, which is inspired by the eponymous J.S. Law novel, follows disgraced military detective Danielle ‘Dan' Lewis, who is sent to investigate a case when a dead submariner is discovered aboard the British nuclear submarine Tenacity. But when the case turns to murder, it puts her in conflict with Tenacity's crew, her Navy superiors, and into the crosshairs of an assassin who has infiltrated her nuclear base with an agenda that will not only destroy national security but kill Dan and everyone she loves.