Red Lightning is a loose sequel to Red Thunder, an homage to Heinlein's juuvenile novels (hands down his best works, BTW: tight, fast-moving, and funny-inspirational), especially Rocketship Galileo. In Red Thunder, an idiot-savant Cajun physicist invents a physics-defying power-supply that his young cousins use to travel to Mars -- after paying a local graffiti tagger to burn a huge mural down the side of their spaceship. It's boys-own-adventure sci-fi with sex and cussing, and it's just the kind of book that I've loved to hell and back since the age of 13 or so.
Red Lightning is much darker, but also even better. It's the story of the next generation of "Martians" who live on a tourism-driven Mars made possible by the power-source detailed in the first book. Ray is the son of Manny, the hero of Red Thunder, and he's a Martian the way that Heinlein's protagonist in "The Menace from Earth" is a Loonie (just one of many loving, sly nods to Heinlein in this book). He ends up on Earth after a natural disaster threatens his family there, and finds himself embroiled in a Katrina-style search-and-recovery mission -- but he's also exposed to the state of the planet, which is not so good.
Earth has been overrun by Homeland Security. The Internet disappears for days at a time, or is blacked out in some regions. Armored, faceless goons maraud and imprison in the name of "security" with impunity. Ray barely makes it out, and when he does, he's glad to return to the sane and gentle environs of Mars -- until the Homeland Security types land there, too.
Heinlein was an ideological libertarian. You could call his politics right wing, and they were, on many of the left-right axes. But Heinlein never would have sat still for the Patriot Act and the daily and deep incursions on liberties that have come to characterise life in America and increasingly Britain and other parts of the world. He never would have accepted that you had to take away freedom to save liberty.
It's easy to forget that today, amid all the debate, to forget how authoritarian we've become, how much we're willing to put up with today -- indiscriminate wiretapping, illegal detention of "enemy combatants" and a TSA with the charm of Stasi goons and the moral instincts of a viper.
Varley brings it home for us, tells us what old man Heinlein would have said about all of it. And he does it in the frame of a cracking, exciting space-adventure tale that'll have you laughing and cheering as it goes (especially when the vaderoid Homelanders try to take Mars and get destroyed by their own lack of acclimation to low gravity).
There are few writers whose work I love more than John Varley's, purely love -- but now that I've finished Red Lightning, I love his stuff even more.