The Podkayne of Mars follows a teenage girl named Podkayne "Poddy" Fries and her younger brother, Clark, who leave their home on Mars to take a trip on a spaceliner to visit Earth, accompanied by their great-uncle. Podkayne is a bright, adventurous sixteen-year-old whose ambition is to become the first woman deep-space pilot.

The trip suddenly becomes extremely dangerous when they take an unexpected detour to Venus, and she gets involved in a volatile diplomatic and political situation involving her uncle.

The book is a first-person narrative consisting of the diary of Podkayne Fries, a 15-year-old (Earth years) girl living on Mars with her parents and 11-year-old brother Clark1.

The book explores
themes such as gender roles, family relationships, and politics and has been noted that Heinlein's portrayal of Podkayne as a strong-willed and independent young woman was ahead of its time.

Heinlein was extremely
unhappy with the change in the ending the publisher insisted upon when it was first published. This edition restores the original ending Heinlein wanted.