This is a sequel to Red Thunder. It's mostly self-contained, but the technological McGuffin is explained more in the first one, and some of the characters carry over, though there is a generation between the two books.
The story starts with a major disaster on Earth and devotes an excessive number of pages to just how horrible the disaster would be. Then a strange series of consequences from the disaster create an exciting but not very sensible plot. I guess a lot of of the plot really does follow from the initial assumptions, but the way it unfolds points up how unrealistic those assumptions are. There's some pointed and on-point criticism of the nature of our government (which is especially interesting to read in light of the fact that in the afterword, Varley claims that he had already written the book before Katrina; if so, he was chillingly prophetic).
The story begins with the main characters on Mars witnessing a major disaster on Earth: an object traveling at relativistic velocity hits the western Atlantic Ocean. An 80-foot tsunami inundates the eastern United States, including Daytona Beach where Ray's grandmother lives, so the family hops on a ship to rescue her. Varley does a pretty good job of envisioning the physical and social results of the disaster, but he drags it out much longer than I think it needed to be. Then they return to Mars and the real story starts. Ray and Evangeline, the daughter of an employee at the Red Thunder hotel (the family business), became an item on the trip to earth, and were having a private interlude on Phobos and didn't hear that Earth had invaded and taken over Mars. Before leaving Phobos, a FedEx man comes to Ray's private apartment to tell him that he has a package that's too large to deliver so Ray should pick it up. Then Ray and Evangeline return to Mars on Ray's personal rocket "surfboard", only to be almost killed by a fighter plane on arrival, arrested, and taken for harsh interrogation by people who won't identify themselves. Apparently Jubal, the idiot-savant inventor of the Squeezer technology that powers the rockets and everything else in the solar system, is missing, and their anonymous captors believe Ray's family (who are adoptively Jubal's family) must have information. Ray of course knows nothing; eventually they let him go, and he discovers that Mars, previously too busy making money to care about politics, are massively protesting the kidnapping of his family. He's the last to be freed. Jubal's brother Travis, Ray's "uncle", tells them the big secret: Jubal has vanished, and when he vanished, he disabled all of the primary Squeezers (the machines that create the bubbles) on Earth. Since the entire economy of Earth is totally dependent on free energy from Squeezer bubbles, Earth is very concerned. Somewhere in here, another equally anonymous force from Earth tries to invade and is repelled by the first. FedEx calls to remind Ray about the package that he never picked up. He collects the box and unpacks a four foot perfectly black sphere. Then he activates the last toy Jubal sent him and the black bubble disappears, revealing (to my complete non-surprise) Jubal. Who tolerates zero G very badly. They manage a scheme to get Jubal to the surface. About this time, a third invasion arrives from earth. In this battle, one of the fighting ships crashes close enough to the main city to do significant damage and kill some people, so now the Martians are really pissed off. They sneak Jubal into a rental space vehicle and rendezvous with Travis' space yacht, which the first invaders have been chasing for a while. Jubal changes the primary Squeezer on board the yacht to make "Stopper" bubbles like the one he mailed himself to Mars in. Travis fails to convince the pursuers to back off, and finally uses his Squeezer to make the three ships vanish. He comments that anyone who expects a ship named the Second Amendment to be unarmed is being pretty dumb. On Travis' ship they finally have time to talk to Jubal, and his situation is fully explained. He was a prisoner in his Falkland Islands laboratory, and he tolerated his situation, but he felt personally responsible for the disaster, which was caused by a Squeezer-powered starship being used as a weapon, and he decided to handle the situation by taking the Squeezer away from earth. Jubal's motivation is pretty hard to follow, but he isn't supposed to be normal in the head. Travis and crew are trying to figure out what to do about Jubal and their situation, and finally come up with demanding that Earth surrender, by using their Squeezer to create two Sun-sized bubbles just over Earth's poles. This looks impressive, but I'm not quite sure why it's supposed to intimidate Earth's leaders into submission. Their secret threat that they will Squeeze the whole planet does cause Earth's leaders to capitulate. They return to Mars and challenge an independent Mars to come up with a system they can trust to take care of Jubal safely; otherwise, they say, they'll pack up and move to Pluto.
The plot as I've presented it is weak enough, but two other things really undermine it for me. First, the fact that the tsunami was caused by a starship made from a small asteroid hitting Earth at .999 or .99999 (Varley's inconsistent on the number of 9s) c is painful. At that speed, a baseball would cause the kind of disaster portrayed. An asteroid would certainly turn the entire Earth (and possibly the whole solar system) into plasma. Second, I just can't swallow how Jubal, who in so many ways has the mind of a six year old, is so far ahead of the rest of the world in his understanding of physics that in the generation between Red Thunder and Red Lightning, no one else has managed to get the tiniest clue of how the Squeezer works. It's just too magical.
The writing from scene to scene is quite good, there's some fine adventure, and there's some good political points, but the plot holes are so big that the story fails to hang together as a sensible whole. I can't really recommend it. 6 out of 10.