Nigel Marven's adventure with dinosaurs of the deep prehistoric seas begins 230 million years ago, where he wrestles with the reptilian Nothosaurus, and meets a biological enigma.

Nigel visits the Eocene epoch, and encounters a pod of small whales before experiencing the world on the brink of an ice age, 4 million years ago.

Nigel Marven visits the Jurassic period, where he encounters the scary Liopleurodon, and the Cretaceous era to see a "Hell's Aquarium" full of nasty creatures.