I'm now two thirds of the way through Sean Williams' non-stop action-packed SF trilogy Twinmaker - I finished the second book, Crash, this morning.
The first Twinmaker book, Jump, introduced us to a world where anyone can hop around the world any time they like through a teleport device called d-mat and the d-mat in its turn makes it possible to create anything from food to building materials using the fabber(presumably short for fabricator). This has freed up most people from work and hunger, though of course there are still some people working, such as teachers and "peacekeepers" (sort of a cross between the army and the police force), but you can live in Sweden and go to school in California if you like. There are also some spoilsports such as the Abstainers who don't trust anything that can take you apart and keep a pattern of you - and who know that accidents do happen, whatever others say. It has happened to them or those they love.
In Jump, ordinary teenager Clair somehow got caught up in something known as Improvement, which she suspected had done terrible things to her best friend. Quiet, shy Clair somehow ended up running for her life and desperately trying to save her family and friends and, by the way, the world. At the end of the last book, Clair blew up a space station she thought was the problem, and escaped only because of the help of her friend the AI known as Q. But Q leaves her...
Crash brings more of the same, as things get worse and worse after the turn-off of the d-mat system, which was necessary since it was producing more and more "dupes", something that can be done once your pattern is stored in the d-mat system. These dupes aren't actually the people whose bodies they ride, just the bodies with someone else inside. They don't last long anyway, but can be produced again.
But there are dupes appearing anyway. Some of them look like people you love. They just aren't. Who can you trust?
Again, Clair makes mistakes while trying to save the world.
It's amazing how much character development the author manages to fit in while his characters are running around a scary world, trying to survive, and there's no individual villain at this stage.
As in the first book, this one ends with a Twinmaker short story seen from the viewpoint of Clair's friend Tash, who was stuck in the middle of a climb in South America when d-mat went down. It's interesting, actually, to see who Clair's "besties" are. In most YA fiction the heroine's friends are not especially interesting in their own right, because otherwise how can you focus on the protagonist? But Clair's friends are very interesting. Tash is brave and intelligent and Ronnie is the computer geek who is able to help Clair with a truly thorny problem early in the book, via the Air(the developed form of the Internet that everyone accesses through special contact lenses). You don't find out much about them early in the series because Clair is on the run only a few chapters in, but as the novels go on, they too develop. Strange to think the whole series so far takes place only over a week...
If you're keen on this universe, there's a short Twinmaker story in Andromeda Spaceways Inflight Magazine #61. It doesn't feature any of the characters from the books, but it does explain some things.
Now on to Book 3!