While visiting their grandparents in Florida, Gabby and Maddox join the Children's Astronaut Program. Shortly after liftoff on what should have been a routine trip to the Space Station, Gabby and Maddox find themselves adrift on a ship with no power. Thankfully, the siblings are rescued by a purple alien named Spark from a planet called Ubatuba. He recruits them to solve a baffling mystery, and in exchange, he promises to take them back home. They quickly learn not everything is as it appears. Meanwhile, Cody and Bindi embark on a rescue mission to save their friends, but will they make it in time?