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.