Antoinette Bookwright didn't intend to endanger the world, but it's not her fault she was woken early on a Saturday. Before her yawns fade, Antoinette finds herself aboard a rocket to harpoon an asteroid that her mother, Sarka, discovered minutes ago. Its mineral wealth could pay off their family business' debt, but the laws of space mining dictate the asteroid belongs to whoever captures it first.

All goes according to plan until the asteroid breaks apart during the capture attempt. Thanks to Sarka Bookwright's most famous invention-a device that can control gravity-they survive the disaster only to discover a fragment of the asteroid is now on course to crash into the Earth. Before Antoinette and her mother can identify what caused the accident, the news breaks and the government orders her mother's arrest for reckless endangerment (of everyone on Earth).

In the seven days the Earth has left, Antoinette must help her parents and their robot teddy bear, Gimini, make peace with their pursuers in order to work together to deflect the asteroid.