A treasure hunt into the deepest cave system in Europe takes a turn for the worst. Now, rather than treasure, it is survival that is at the forefront of the spelunkers' thoughts. But their attempt to escape out of the dark deep places is thwarted. Men are not at home in the depths. But there are things that are... pale terrifying things. Huge things. Things red in tooth and claw.

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.

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.

The fossilized remains of a previously unclassified hominin species are discovered in the Altai Mountains, prompting teams of scientists from around the globe to converge upon this isolated region of Siberia in search of further evidence to corroborate the revolutionary theory that a third proto-human ancestor coexisted with Neanderthals and primitive Homo sapiens. What awaits them is anything but extinct.

Alex Hunter - in the mission that turned him from a normal man into the weapon known as the Arcadian - and the elite team of soldiers known as the Hotzone All-Forces Warfare Commandos must enter a hostile country to rescue a defected Chechen researcher from the centre of a country at war. But the HAWCs are not the only ones looking for the rogue scientist and the mysterious package he carries with him. A brutal and relentless killer and his death squad are on the trail, too - and they bring a savagery with them that Hunter and his team have never witnessed before in modern warfare.