The secret location of the Vanguard Islands is no longer a secret ...

Tired from years of fighting, Xavier passes the crown to a younger Hell Diver, Kade Long, and then sets off on the Sea Wolf with Magnolia to find Michael and his family. But the journey will push them both to their limit.

On the damaged airship Vanguard, Michael and crew are running out of water and must dive to a new location before attempting the perilous voyage across the Atlantic to a new home.

Back at the Vanguard Islands, King Kade hurries to prepare the rigs' defenses against the Forerunner and his Knights of the Coral Castle. Fearing that X won't return with the airship in time, Kade sends the elite Barracudas on a mission to find aircraft that will give the islands a fighting chance against the knights.

In the penultimate Hell Divers book, the survivors travel skewed and far-flung paths, but soon those paths will converge. The journey is almost over, so strap in for the last dives!