After narrowly escaping the supernova that consumed Mars, Liam and Phoebe are desperately trying to catch up to the starliner that's supposed to take them to their new home planet on the other side of the galaxy. Their ship is fast enough, but unbeknownst to Liam, Phoebe t a human at all, but part of an alien race intent on stealthily sabotaging the colonists s been subtly throwing them off course to delay their rendezvous with the ship. Meanwhile, Liam experiments with the alien time-travel watch and discovers far more than he bargained for. With the same enthralling, cinematic pacing he used in Last Day on Mars (2017), Emerson unspools nail-biting suspense in this sequel, all while employing a solid grasp of real science and paying homage to classic sci-fi stories. Through all the engrossing sci-fi action, however, Emerson keeps the plot solidly grounded in the characters, who are vivid and complex. A cliff-hanger ending promises deepening adventures in forthcoming volumes, which middle-grade sci-fi fans will be eager to get their hands on.

In the aftermath of Earth's sun going supernova and the alien attack at Saturn base (Last Day on Mars), teens Liam and Phoebe plan to rendezvous with colonists at refueling-station planet Delphi. But Phoebe has a secret: she's not human. Rife with tension, time travel, and unexpected twists, this conceptually expansive science-fiction novel relies strongly on the human element to grab--and hold--readers' sympathies.