For centuries, it has lain dormant. Now, it has awakened, and is plagued with an insatiable appetite to kill. On a small island on the Louisiana coast, prospects for a better life grow fewer with each passing year. So, when a mysterious blood red pearl is discovered, John Hightower and his friends begin diving in search of more. Soon, however, relationships are put to the test and lifelong friendships begin to unravel amid a flurry of betrayals, lies, and death. Meanwhile, something stirs in the sea; a creature of unimaginable size, with a fury matched only by its hunger. Feared by every living thing in the sea, it now seeks to feed on those who rule the land. Before long, John witnesses his companions ravaged one after another. As the body count rises, the group must try and settle their differences in order to survive the wrath of the MOLLUSK.