For centuries, the scattered islands of the Archipelagos have been bound together by oohnica—a force as natural as wind, tide, or gravity, yet harnessed only by aghitas: groups of four people trained to think, act, and feel as one.

Around this strange discipline, universities have risen, realms have prospered, and an uneasy peace has lasted long enough for war to become a subject of history lessons.

Jiro arrives at the University of Eine pursuing a dream: to join an aghita, master oohnica, and become a navigator like his ancestors. But the group that chooses him is anything but ordinary. Led by a brilliant student with more ambition than patience, it includes strangers, rivals, and someone whose innate talent for oohnica should not exist.

At first, their troubles seem like the ordinary struggles of any young aghita learning to work as one. But soon the signs are impossible to dismiss: oohnica is changing—or perhaps revealing that it was never what the scholars believed it to be.

As Jiro’s dream and the old peace both come under threat, he and his companions must leave the safety of the university walls and follow the mystery across the sea.

What they discover could remake their understanding of the world and of one another—and expose the powerful factions already moving to reshape the future of the Archipelagos.