On the overnight shift at the Allen Telescope Array, Devin Marsh watches the hydrogen line and expects nothing. The pipeline flags a return as noise. Years of false alarms have taught him not to get excited, but this time he cannot look away.
The signal seems to come from beyond Pluto, where world astronomers have hunted for decades. Planet Nine is radiating heat and holding an atmosphere it has no business having.
Now, someone or some thing is transmitting from it, and someone was listening. Earth answers. Then it builds a ship.
Thirteen months of hard travel stand between the Halcyon and its destination. Commander Ray Ostrowski believes in procedure. Mission specialist, Dr. Elena Marchetti, believes in context. Neither one knows what to expect.
