"170 years ago, in a world where humans have evolved such that they could live on the ocean floor, and form cities there, Commandant Franklin led a hunting party on a reconaissance expedition north, traveling from the outer edge of the Indian Ocean, all the way to the High Arctic. His goal: to find the fabled Northwest Passages for the Vicegerent of Tridention, and establish business with underwater arctic cities there. But the expedition went awry, and they never returned. Everyone in the party was presumed dead.
Until now.
When two of the hunters from that same expedition find their way back to Tridention after all these years, Watson, a retired commandant for one of Tridention's thirty-five hunting parties, agrees to help those hunters form a ragtag party of their own, against their leadership's wishes, and travel all the way back to the same Northwest Passages to recover the rest of the hunting expedition. The hope is that their commandant, and other hunters, are somehow still alive and can be brought back home safely. "