On an uninhabited island 20 miles off the rugged Scottish coast, three lighthouse keepers begin a six-week shift. As Thomas (Peter Mullan), James (Gerard Butler) and Donald (Connor Swindells) settle into a quiet, daily routine, something unexpected and potentially life-changing happens - they stumble upon gold. Where did it come from? Whose does it belong to? A ship appears in the distance that may hold the answers to these questions - what follows is a fierce battle for survival that, fueled by isolation, paranoia and greed, sets three honest men on a path of destruction.