In Mr. Heinlein's cosmos, interplanetary rocket travel is old stuff. Earlier books got his characters to the moon and to stations parked in space. [In "Red Planet"] he describes colonial life on Mars some years after men from the earth have settled there. He even throws in a desperate revolt against dishonest agents of the operating company back on earth.

When Jim and Frank, sons of colonials go to boarding school they take Willis, a Martian called a bouncer, about the size and shape of a volley ball. A charming, friendly creature, Willis can record and play back long stretches of conversation. It is Willis who records the plotting of the crooked agents and thus starts the revolt. Before justice triumphs, the boys have many terrifying experiences skating endless miles down a Martian canal. They visit mysterious Martian cities deep underground and talk with even more mysterious natives.

Mr. Heinlein is so straightforward and matter of fact in recounting all this that it's pretty hard not to believe every word of it.