When Don Harvey's parents abruptly summon him from school on Earth to join them on Mars he has no idea he's about to be plunged into a deadly interplanetary intrigue. But from the moment he begins his journey he finds himself the subject of intense – and possibly deadly – scrutiny. Things only get worse when the ship Don is traveling on is unexpectedly diverted to Venus, where the colony has launched a revolution against Earth's control. Flat broke and homeless, Don will have to muster all his resources to stay alive – though it does help that he has earned the friendship of a Venerian dragon known as "Sir Isaac Newton." A riveting coming of age story set against a backdrop of a war between planets, this classic Heinlein novel crackles with action, adventure, politics, wit, and brilliant speculation about the world to come.