Far Travels, The Gracchian Adventures, Book One

Far Travels is an adventure set in the near future. The Ellsworth family—Abby and Tom, age 11, and their adoptive father Oliver—must emigrate to the planet of Gracchia. The adventure culminates in the Bonebreaker Race, a multi-species event that combines aspects of a scavenger hunt and a speed race. But during the event, Abby and Tom become aware that not all is as it seems on Gracchia.