Broke and desperate, paleontologist Grant Coleman gets the chance of a lifetime exploring a long-sealed cave, the fabled home of a gigantic creatures. NPS Ranger McKinley Stinson discovers a rancher’s prize bull has been butchered by an airborne killer, and tracks the blood trail back to the re-opened cavern. But as she’s about to arrest the trespassers, the unstable roof collapses, trapping all.

A man of great power and wealth, Robert Jensen wasn't content with the ordinary. His drive to conquer the world led him to its darkest corners. There, he began to assemble a collection of monsters beyond belief - Sasquatch, Thunderbirds, Skunk Apes, and more.

A deep sea fracking operation in the Arctic Ocean breaks through into a world hidden for 15-million years, an undersea cavern from the Pliocene Epoch of the Cenozoic Era. Among the prehistoric terrors unleashed is a giant megalodon, a shark so efficient it had no need to change for 20-million years. Asa Iverson was the only survivor from the Global Kulik incident. Now, the nightmares haunt him. Did he see a colossal shark long thought extinct, or was it a hypothermia-induced hallucination?

On a desolate beach in far northern Scotland, the winter storms have been washing up all manner of things since time began. But buried in the centre of one smaller iceberg is a shard of ancient Viking pottery telling a partial tale of a hidden mysterious island beyond the ice and mist, that was home to a great treasure and even greater horrors. Thawing in the same block of ice was a rotting flap of skin that refused to be identified but had similar skin patterns to a creature not seen for 100 million years.

Down there, beyond the deepest caves, below the crust and the mantle, there is another world. An old woman locked away in a Russian asylum has a secret - knowledge of a 500-year-old manuscript written by a long-dead alchemist that will show a passage to the mythical centre of the Earth. She knows it’s real because 50 years ago, she and a team travelled there. And only she made it back. Today, caving specialist Mike Monroe leads a crew into the world’s deepest cave in the former Soviet Union.