The fifth book in Robert Heinlein’s science fiction series for young readers is different from the ones before it in that it’s written as a suspenseful thriller rather than a typical boys’ adventure. Don Harvey attends a private school in New Mexico where riding is a feature activity while his parents are on Mars doing scientific research. He’s surprised when they suddenly send word and a rocket ship ticket to join them on Mars, but talk of war between Venus and Earth as been growing, and his school is happy to see him leave. Don was born in space and claims dual citizenship from Earth and Venus. Don’s parents have told him to contact their old friend Dr. Jefferson in Chicago the night before his ship leaves, and Don and the doctor attend a nightclub show where the power goes off suddenly. Dr. Jefferson is worried, and they return to his home, but security officers are waiting for them there and Don is interrogated before being released at his hotel. Before this happened, Dr. Jefferson had sent Don a package and impressed on him the contents must urgently travel with Don to his parents on Mars. When the package arrives, it holds only a cheap plastic ring, which Don decides to wear. Another police interrogation examines the ring but deems it harmless. Before boarding his ship to the orbiting space station where he will transfer to a Mars rocket, Don meets a Venusian, a dragon-like creature with the English name Sir Isaac Newton. They become friends, and when trouble erupts on the space station, that friendship helps him. Venusian freedom fighters have taken over the station, and plan to destroy it. The only options for Don are to return to Earth or join the rebels and travel to Venus, which he agrees to do. Throughout the book, Don is constantly thrown from one kind of trouble to another, and his eventful time on Venus is no different as war erupts.
This is an exciting story and I enjoyed reading it again. Recommended.