While diving in a remote French lake, a couple of YouTubers who specialise in underwater exploration videos discover a house submerged in the deep waters. What was initially a unique finding soon turns into a nightmare when they discover that the house was the scene of atrocious crimes. Trapped, with their oxygen reserves falling dangerously, they realise the worst is yet to come: they are not alone in the house.
A deep-sea submersible, part of an international undersea observation program, has been attacked by a massive creature, previously thought to be extinct, and now lies disabled at the bottom of the deepest trench in the Pacific with its crew trapped inside. With time running out, expert deep sea rescue diver Jonas Taylor is recruited by a Chinese oceanographer to save the crew – and the ocean itself – from this unstoppable threat: a pre-historic 75-foot-long shark known as the Megalodon.