Voyager in Night by C.J. Cherryh
It's been a couple of weeks since I read this, so I'm not sure how good my memory of it is. Anyway, I found it the most difficult of the Cherryh books I've read to understand in the first place, and it's also the weirdest and creepiest of the three "magic mushroom" novels collected in the Alternate Realities ominbus. The other two, which I've previously reviewed, are Wave without a Shore and Port Eternity.
The scenario, to the extent that I understood it, is that three humans -- a brother, sister, and childhood friend who has married the sister -- have scraped together enough money to buy a cargo ship, and they are working in a star system when a large alien ship of some kind swoops in and grabs them. All three of them are scanned, and two of them are painfully killed. The two who were scanned are then re-embodied and begin to interact with the survivor. Further scans are made of, I believe, all three, and then some of those scans are re-embodied, so that there are multiple versions of the characters with different memories depending on when they were scanned and re-embodied. That's part of what makes the book so confusing, and then on top of that all the aliens are referred to with names that consist of non-letter characters, often nested in ways that are slightly different but look very similar.
It's also a horror story, which is not my favorite genre by far. Terrible things happen to all the human characters, and it appears that the aliens are experimenting on them for obscure purposes. By the time I got to the end, I was pretty much completely lost. I had literally lost the plot and didn't understand the resolution. Still, it scores extremely high on the wild-ass weirdness scale, and once again I give Cherryh a lot of credit for writing something so strange and different from her other work, and to DAW for publishing a book that wasn't even remotely commercial in nature. Those were the days, by grab! 1984, to be exact. That seems appropriately dystopian, in fact.