Something tragic has happened at Purgatory Crater on the far side of the moon. Three astronauts are dead and a fourth is trapped inside Purgatory Moon Base. Commander David Holtz, leader of the rescue and recovery mission, expects to confront the horrors of asphyxiation in the vacuum of space. But what he and his team find is worse than they could have imagined. As they piece together the chaotic puzzle, it becomes clear the survivor, George Dobson, has gone mad in his months of solo confinement. But is he really crazy? Or is he hiding a deeper, darker secret?