A giant boardwalk has been resurrected high up in the Indonesian rainforest canopy, offering guests stunning, spectacular, and unparalleled views of the rainforest. However, the boardwalk is incomplete and in need of more funding. The creator, John Corstine, assembles a group of potential investors for a weekend tour of the boardwalk. Little do they know that high up in the rainforest canopy, they are being watched, but more importantly, they are not alone.

Fresh off an expedition to the wilds of Indonesia, Bick Downs returns home to his beloved San Francisco. It isn’t long before he learns that an ancient species of predator has been released and is running amok in the city. He joins forces with others in an attempt to capture the mysterious creature, only to learn that up north, in the sleepy agricultural town of Santa Rosa, California, something even more terrifying and sinister has been created.

Bick Downs and the Society of Cryptozoological Agents are dropped into the lush bamboo forests of Vietnam. They are searching for Gigantopithecus, the largest primate that has ever existed. But what they find deep and entangled amongst the trees is not the reclusive giant that roamed the bamboo forests of Southeast Asia several million years ago. Instead, they find something else entirely. The animal has evolved.