This is the story of a family (named Stone) who go on a trip together to Mars and the asteroid belt. The father, Roger Stone, is a colorless disciplinarian; the mother, Doctor Stone, is a dull drone, but the main characters, Castor and Pollux Stone, are youngsters who have a bit of attitude--they get into trouble,and like to make money. Hardly compelling stuff, but a step up from the two-dimensional characters of other early Heinlein novels. The most interesting character is the vinegary grandmother, Hazel Stone, who often sides with the boys in their adventures.
The story starts out with the family buying and prepping their own family spaceship, and then describing the trip through space to Mars. Then on Mars the boys run afoul of local bureaucrats when they try to engage in a bit of local enterprise. Finally the story tracks the trip to the asteroid belt, and describes what the asteroids are like. It's a reasonably entertaining story.
This report prepared by steve