One hundred and fifty million years ago, dinosaurs ruled the land, but the oceans were dominated by a mysterious sea monster. Meet the pliosaur, the Tyrannosaurus rex of the seas! Now, a giant skull has been found in the cliffs of the Jurassic Coast.

The film follows Sir David Attenborough as he investigates the discovery of a lifetime. He is joining two of the UK’s most intrepid fossil hunters, Steve Etches and Chris Moore, on their perilous expedition to excavate the skull from its resting place 12 metres up on the cliff face. Sir David has been an avid fossil collector since he was a young boy but has never come across a find quite like this.

The first piece of this Jurassic puzzle was discovered purely by chance. A fossil enthusiast walking on a beach near Kimmeridge Bay, Dorset, one morning spotted what looked like a large piece of driftwood. But he soon realised it was something far more remarkable! It was the snout – just the tip – of an enormous pliosaur skull. Fossil expert Steve Etches was called in, and knew that the find was hugely significant. He also suspected the rest of the skull was still in the cliff, so he quickly embarked on the huge challenge to extract it.

Using the latest technology to help unravel the skull’s mysteries, an international team of scientists and palaeontologists search for clues about how this fearsome beast not only looked but how it behaved, and the strategies it used to hunt its prey.

Sir David visits the University of Southampton, where a CT scan of the snout reveals an astonishing network of blood vessels and sensory pits, which would have helped the pliosaur to hunt even in the deepest, darkest water. And at Bristol University, Sir David discusses a 3D model made of the pliosaur skull, and finds out that the pliosaur had a bite force of around 32,000 newtons: twice that of a saltwater crocodile, which has the strongest bite of any animal on the planet today.

Cutting-edge visual effect sequences bring the sea monster to life, showcasing its astonishing size – thought to be an incredible 12 metres long – and its phenomenal strength. A momentous new discovery, scientists now believe this could be a completely new species of pliosaur.

Attenborough and the Giant Sea Monster combines groundbreaking science, fascinating natural history, gripping storytelling and state-of-the-art CGI to explore the tale of the most formidable predator of the Jurassic world – one that hunted in the seas just off the coast of Britain.