Salvage and Demolition by Tim Powers

Powers is not particularly prolific. But, over the last decade or so, he does seem to come out with a novella or two vaguely related to his most recent novel -- perhaps reworked sections that didn't fit, or early abandoned/superseded versions of his premise, or maybe just something else he worked on while the big book was stuck somewhere. (I don't know his writing process; I just read the things.) And so Salvage and Demolition, a novella-as-book, came out two-and-a-bit years before his novel Medusa's Web, and then I read both of them, not entirely deliberately, within a month and a half.

Salvage is a time-travel story -- well, really more of a time-slip story, in which a man from the modern world is pulled back to the 1950s through some artifacts he discovers, bouncing between the two times over the course of the story, and gets caught up with a woman then and an apocalyptic cult existent in both times. I don't want to say much more, not least because the book went back to the library two months ago. It's tight and precise and lovely and has a perfect bittersweet ending. And it is a novella, of only about 21k words. So you should just read it. You should just read any Powers books, but the shorter ones take even less time.

(And, to my first point, the time-slip mechanism is very similar, but not identical, to the one in Medusa's Web, so Salvage does feel like a cousin or small sibling to the larger novel. Reading the two in close succession is recommended.)