In the Micronesian Islands, a top secret, U.S. government–sponsored undersea lab conducting vital biomedical research on a rare jellyfish known as the Blue Medusa suddenly . . . disappears. At the same time, off Bermuda, a bathysphere is attacked by an underwater vehicle and left helpless a half mile below the surface, its passengers - including Zavala - left to die.
Only Kurt Austin's heroic measures save them from a watery grave, but, suspecting a connection, Austin puts the NUMA team on the case. He has no idea what he's just gotten them all into.
A hideous series of medical experiments . . . an extraordinarily ambitious Chinese criminal organization . . . a secret new virus that threatens to set off a worldwide pandemic. Austin and Zavala have been in tight spots before, but this time it's not just their own skins they're trying to save - it's the lives of millions.