Quin Black spends most of his time on the Outer Rim of Ziri, the donut-shaped planet he calls home. His role in the military is to step through Doors, portals leading to locations all over the universe, for a variety of reasons ranging from diplomatic work, to rescue missions, to trade, and more. But after he is called back home unexpectedly for undisclosed reasons, he is shocked to find out that it has nothing to do with his job. Rather, it’s personal: his own father, a highly decorated planetary scientist, has disappeared. And behind him, he’s left something strange and potentially deadly: a brand-new type of Door, never before seen. And it seems to somehow be connected to every other Door in existence. Quin’s closest friend, a brilliant scientist and mathematician named John, quickly discovers that the existence of this new Door could have disastrous consequences for everyone everywhere. And the fastest way to solve the problem? Find Quin’s father. While Quin is happy to work within the system, John has no such compunctions. He leaps through the new Door, and when Quin tries to stop him, he gets dragged along for the ride. Together, they much traverse new worlds, searching far and wide for Quin’s father, with the hope of preventing a catastrophe that could end lives and entire civilizations across the universe.