This two-part programme explores the world of deep-sea killers, revealing mysterious creatures using cutting-edge CGI. We meet the Anglerfish, which lures prey with its glowing spine. The giant Dunkleosteus, a prehistoric fish, is brought back to life with a mechanical bite force test. Adventurer Steve Backshall uncovers the secrets of the Stoplight Loose-Jaw, while biologist Dr Jennifer Hoyal Cuthill reveals the terrifying Thalassotitan, an evolved predator that moved from land to sea over millions of years.