Rugged adventure guide Ron Combs leads a group of thrill-seekers to an island off Washington's coast. But when devastating lava flows destroy their boat and overtake the island, Ron and his clients are forced one-by-one into the sea, where a gigantic prehistoric predator awaits. Trapped between the lava-covered island and the huge jaws of an ancient shark, Ron teams up with his client Rachel to devise a way to keep everyone safe...even if it means sacrificing himself in the process.