In four years, aerospace giant Prime Space will put the first humans on Mars. Helen Kane, Yoshihiro Tanaka, and Sergei Kuznetsov must prove they’re the crew for the historic voyage by spending seventeen months in the most realistic simulation ever created. Constantly observed by Prime Space’s team of "Obbers," Helen, Yoshi, and Sergei must appear ever in control. But as their surreal pantomime progresses, each soon realizes that the complications of inner space are no less fraught than those of outer space. The borders between what is real and unreal begin to blur, and each astronaut is forced to confront demons past and present, even as they struggle to navigate their increasingly claustrophobic quarters—and each other.