In some ways, the American search-for-life mission to Mars had been a great success. As predicted by geologists, groundwater was discovered under the planet’s frozen, sterile surface. More importantly, microbes were found living in that subsurface water, validating the idea that life could exist anywhere in the Universe where the right conditions were found. But the mission had also been disastrous. Two of the astronauts had been lost in an intense, sudden dust storm—and never found. For the survivors, it was a morose homecoming, facing the friends and families of their marooned companions. But the returning astronauts also harbored dark secrets about what had been found on the red planet. Back on Earth, two scientists—an exuberant exobiologist and a down-on-his luck microbiologist—are thrown together in an attempt to determine what really happened on Mars—and to save humanity from a terrible fate.