After a shipwreck, Chen Ye and eleven other survivors drift to an isolated island shrouded in mist. They soon discover that a gigantic monster lurks on the island, capable of imitating human voices. At night, it follows cries for help and drags their companions into the darkness one by one. To stay alive, the survivors take refuge in an abandoned underground shelter on the island, only to discover unexpectedly that the island is actually an out-of-control breeding facility for ancient creatures. Behind the sealed iron doors, as more companions fall victim one after another, fear and selfish interests gradually divide the group. Some risk their lives to protect everyone, while others betray their companions and flee in a desperate bid to survive.