Perched on a bleak and inhospitable rock off the coast of Scotland, the Hallowsay Light has guided sailors for over seventy years. Now its beacon has gone inexplicably dark, imperiling the ships that ply the waters of the North Atlantic. The news has reached the lighthouse tender Helios, already steaming toward the island of Hallowsay for its fortnightly relief of the station. A search party, made up of three volunteers from the crew of the Helios and a relief keeper, is sent to investigate. What awaits them are horrors from beyond!