The first sixty percent of the story follows young protagonist Matt Dodson as he undergoes rigorous training as a cadet in the Solar Patrol Space Academy. While there, he befriends fellow cadets Tex Jarman, Oscar Jensen from the Venus colony,  and Pierre “Pete” Armand from Jupiter’s moon Ganymede.

Upon graduating from the Academy, Matt, Tex, and Oscar are assigned to the Patrol vessel Aes Triplex on a mission to the asteroid belt to locate the Pathfinder, a vessel reported missing during a scientific mission.

After successfully locating the lost ship, damaged as a result of a freak meteor impact, the Pathfinder is repaired and flown to Deimos, the outermost moon of Mars. Meanwhile, the Aes Triplex is assigned to investigate a deadly native uprising against the crew of the Gary, a merchant vessel that landed in the equatorial region of Venus. The cadets depart the Aes Triplex in a small rocket commanded by Lieutenant Thurlow, who is knocked unconscious after a perilous landing—leaving the cadets stranded in the swamps of Venus. Fortunately, Oscar is well acquainted with the customs of the amphibious natives, but can the cadets maintain peace with the rankled “Venerians” long enough to find a way off the planet and save Thurlow’s life?

Space Cadet differs from some of Heinlein’ other juvenile SF novels—such as Spaceman Jones and Citizen of the Galaxy—in that it does not offer much detail about the main protagonist’s background and is not a “rags to riches” tale. By the time we meet Matt Dodson, he has already arrived at the Academy fresh from his hometown of Des Moines, Iowa and returns home only once for a brief visit during leave. In fact, once Matt, Tex, and Oscar are assigned to the Aes Triplex, the role of the main protagonist is shared among the three.

I found that much of the first 65 percent of the book dealing with the cadets’ training could have been trimmed or condensed. Nevertheless, Space Cadet is a reasonably enjoyable adventure, especially in the final chapters dealing with the Pathfinder and the cadets’ subsequent adventures on Venus.