Fifteen years ago, a ship called “Sirius” disappeared in the asteroid belt. Officially, this is considered a catastrophe, but the last signal pointed to Ganymede—Jupiter’s icy moon, beneath whose surface lies a deep ocean. Lina was left without a father, who had been a lead cryptographer on “Sirius.” Growing up, she became a communications specialist and received an assignment to the “Medusa” station located in those very waters where, perhaps, her father perished. For her, it’s not just a job—it’s the search for the truth. The answers she finds turn out to be more terrifying than any question. In the depths of Ganymede lives a foreign collective intelligence that treats human individuality as a disease requiring cure. Fifteen years ago, her father’s algorithm accidentally established a connection between worlds—and now this bridge has been opened again.