Thomas, James and Donald go to the Flannan Isles in Scotland to keep the lighthouse. All is well on the island apart from a broken radio. After a storm, the three men find a wrecked boat, a locked wooden chest and a middle-aged man who appears to be dead. Donald kills the man in self-defense. The chest holds a large amount of gold, and the three agree to share it out after returning to the mainland and to keep a low profile. A boat arrives from the sea to recover the gold. Locke and Boor come ashore, find Thomas and ask where their crewman Gale and the chest are. Thomas tells them that the body and the chest were shipped to the mainland three hours earlier. Realizing they have been deceived, the two men quickly overpower James, Donald and Thomas, and Locke angrily demands to know where the gold is. James and Donald, still alive, fight back and finally kill both men. In the darkness, James also kills the boy who came ashore with Locke and Boor, which makes him think of his own child. Unable to face himself as a father who kills and lies, James blames Donald and kills him. Thomas takes the chest and leaves the Flannan Isles with James, heading out to sea. After James throws himself into the sea, he calls to Thomas for help; thinking of the remorse and pain of a father and husband, Thomas pushes James back under the water. Director Kristoffer Nyholm skillfully crafts a thriller with a classical flavor, full of striking visuals. On a lonely Scottish island surrounded by sea winds, facing family, responsibility and the uncertainties of life, how can a person, like a lighthouse, give out a glimmer of hope?