I read this book about 15-May-2011. I've read this book before. The book is copyright 1951. This note was last modified Sunday, 31-Jul-2011 18:43:22 PDT.
This note contains spoilers for the book.
While it's so far back in the mists of time that I can't be sure, I think this might have been the first Heinlein novel I ever read. I've always had a fondness for it, and I remember reading it quite often in elementary school (I read The Rolling Stones a lot more often these days). I should probably remind you that the counts in these booknotes only count reads since when I started these notes in 2001; in fact, it's worse than that, because a few books get grabbed for partial or complete random re-reads by accident so often it's not worth trying to keep track; notably Have Trenchcoat--Will Travel and others (#5) and A Civil Campaign (#4), and in really especially low-brain moods, W.E.B. Griffin.
This is more political than most of the juveniles. Don is called home to Mars from school on Earth (though he's never actually been to Mars; but that's where his parents are now), and asked to stop and say hi to an old friend on the way. The friend gives him a ring to take home, a silly bauble and Don incorrectly concludes the wrapping paper is what's actually important.
Then Don is questioned by the security police, and the friend is too, and he dies. Of "heart failure", it says here. .
Don ends up on Venus due to a revolution breaking out there and striking at Earth's station while Don is there waiting to go to Mars. He manages to avoid being killed when Earth invades Venus, and joins the rebel army, and fights, and survives. And eventually connects back up with the Venerian "dragon" that befriended him on Earth, and discovers that Venus and Mars are working together, and the ring has vital scientific data that let the rebels win with new weapons and propulsion technologies.
As always, Heinlein was wearing his own special magic ring when he wrote this—the "ring of authenticity".