In the 24th century, mankind has spread throughout the Solar System, from Mercury (where a moving domed city, Terminator, moves on a track to stay out of direct sunlight) to Saturn (where mankind lives on Titan and other moons) to Earth (which is in somewhat dire shape after centuries of climate change and over-population) to Venus (which is undergoing radical terraforming) to Mars (already terraformed). Throughout the system, thousands of asteroids have been hollowed out, spun up, and used to create mini-ecosystems called terraria, some of which contain ecosystems and species no longer found on Earth, and many of which are put in eccentric Solar orbits that allow their use as a mass-transit system, in conjunction with space elevators on the Earth and other major planets. Small quantum computers, called qubes, have been used to create rudimentary artificial intelligences. Humans have extended life spans of more than two centuries (as in some earlier Robinson novels), and there are new genders beyond male and female. These are just some of the marvels among which sets his story.
The novel's complex, convoluted narrative also supports a diverse cast of interesting characters, whose complicated natures are somewhat slowly revealed. Swan in particular, early in the novel, has the feel of a self-absorbed, impetuous twenty-something, but is slowly revealed to be more than a century old, and a well-known former terrarium ecosystem designer. She becomes more likeable and sympathetic as the novel progresses and her character is more fully revealed. She and Fitz are in many ways opposites in their personalities, but their growing friendship is believable due to the more important similarity of their being both smart and empathic. It is indeed this combination that I think makes so many of Robinson's characters distinctively different from most other SF protagonists -- their deep-rooted empathy not just for their friends, but for all of humanity, and indeed for all life, and even natural landscapes.
Summary (with spoilers):
Swan lives on Terminator, a city on Mercury that glides along planet-wide tracks to avoid being caught in the sun. As Swan grieves at the death of her grandmother, Alex, she learns that Alex was involved in secret political dealings. Alex has left several letters that Swan must deliver, causing Swan to meet up with Wahram, Inspector Gennette, and Wang.
In addition to being overcome with grief, Swan is a rather unusual person. She had her qube, Pauline, installed in her head. She's also undergone various physical modifications.
Swan tries to figure out what Alex was working on, but no one will tell her directly what's going on, except that it has to do with Earth, and that they don't trust the qubes. Swan travels to Earth via terraria (hollowed-out asteroids turned into small worlds), to meet up with her former lover, Zasha. On Earth, some ruffians attempt to kidnap her, but she is saved by Kiran. In return, she gets him off-planet to Venus, where he becomes a double agent for two major political powers.
Swan meets up with Wahram on Mercury. After attending a conference, they decide to don some spacesuits and walk back to the city platform. En route, they witness an explosion the almost hits Terminator and destroys the tracks. They rush back to the city, but it's already been evacuated. Since the sun is rising, they need to get to safety. They decide to run sun-ward to the next platform, which has an underground system mirroring the tracks above ground. They make it to the platform, and while they are waiting for the elevator to arrive, Swan jumps in front of Wahram to protect him from a solar flare.
They hike along the underground tunnel for weeks, trying to reach safety, whistling Bach to pass the time. Swan gets increasingly ill from radiation poisoning. Eventually, they go to the surface to break the monotony, even though they are sun-side, and a vehicle passing by rescues them.
Swan spends time with Inspector Gennette, who thinks the attack on Mercury was caused by lots of small rocks thrown so that they would all land at the same time. He's also suspicious of the qubes. Swan and Wahram go to Earth to help with various development projects and then decide to repopulate Earth with all of the animals stored in the terraria. Thousands of animals are sent through the sky in gel balloons. On Earth, Swan and Warham realize they have feelings for each other.
Swan and Warham become passengers on a space craft, when Pauline informs Swan that a similar attack is planned on the Venus sun shield. They use the space ship to deflect the small projectiles, which means that everyone has to evacuate. Swan and Warham get into space suits and float in space, waiting to be rescued. However, their rescue ship is attacked before it can pick them up, and Warham's leg is injured. Eventually, they are rescued, but their time waiting in space is reminiscent of their time in the tunnel.
Meanwhile, these strange humanoid qubes have been wandering about causing trouble, so Inspector Gennette exiles them all in a star ship. The book ends with the marriage of Swan and Warham.
★★★★☆ (4 out of 5 stars) - I really liked it.
