'Accelerando on downers' is probably not the synopsis Charles Stross would choose for Glasshouse (2006), although it does take the former's (relative) optimism about posthumanism and drastically flip it.
So, let's try again.
In Stross' body of work, Glasshouse is perhaps the equivalent of the 'difficult' prog/metal experiment: all dystopian ideas, arcane technology, ultraviolence and unusual time signatures. And I mean the part about time signatures pretty much literally, since the novel opens with a glossary of time as measured in the far future setting, all kiloseconds, megaseconds and giga.... well you get the picture.
It follows that the convoluted plot, summarised and compressed here, will make limited sense. Key to following it all is comprehending the idea of posthumanism/transhumanism - the theory that in the future technology will allow humanity to transcend its physical and mental limitations and be whatever it or individual members of the species want to be. In twenty-first century space opera (like Glasshouse) this often goes hand in hand with interstellar or at least inter-planetary civilisation.
Done badly or indifferently, it just makes for a lot of hand-waving science-indistinguishable-from-magic special effects. Done well, it also raises questions about the provisional nature of our humanity under technological pressure and the ethical problems which arise whether we embrace or resist change. Glasshouse is one of the latter.
Our protagonist Robin, is an amnesiac posthuman in a new body, recovering from PTSD after a cosmic information war. He volunteers for the interstellar equivalent of Castaway or a gigantic LARP, a psychological experiment in recreating Dark Age (read: twentieth century Earth) society. Needless to say, things aren't quite what they seem.
Stross throws out ideas, leads and lures in such quantities that the book properly fizzes. This is both a strength and a weakness: it takes a while to work out what's going on and at least a couple of sub-plots are left hanging without proper resolution. The antagonists, too, are more sketched out than fully developed in a way which weakens the philosophical elements of the book.
As is traditional, he doesn't quite land the ending either, rushing through it in a few scanty pages. There's a lot going on in Glasshouse and for me it's one of those rare novels that would benefit from more than the 388 pages it has. A Director's Cut, maybe?
This review would also not be complete without mentioning that this is a righteously angry book in polemical dialogue with the present and recent past, particularly with gender roles and the answers provided by (for example) Christian fundamentalism. You can probably guess which aspects of twentieth century American society the experiment tries to replicate with imperfect information, and the resulting body horror places Glasshouse closest in mood (sombre, oppressive, skin-crawling) to The Apocalypse Codex in the Stross canon.
It falls very much into the category of gloriously messy, ideas-driven, heart-on-sleeve flawed-but-fascinating science-fiction novels that I love almost as much as the ones that do all of this and bring it all on home. A rewarding, if occasionally frustrating novel.