Nigel Marven continues to search the ancient oceans for the deadliest sea monsters of all time. He must travel to the Eocene, 36 million years ago, and come face to face to the killer whale Basilosaurus. His next mission will take him to 4 million years in the past to tag the monster shark Megalodon, a shark that makes the Great White look like a minnow in comparison! But that's only if he survives his encounter with Dunkleosteus, the monster armored fish.