by Jack Finney.
Artist Simon Morley is, at worst, only vaguely dissatisfied with his job at an ad agency, drawing bars of soap from every angle, when a total stranger approaches to offer him the chance of a lifetime: to be part of a government project so secret that Si has to say yes or no without even knowing what the project actually does. He says yes, and learns that the mysterious project is investigating the theory that time is not linear, but that all moments exist simultaneously, so that it should be possible for him to walk into the Dakota apartments in New York in the 1970s--and simply walk out in 1882.
Now, I normally try to talk about books without spoilers just in case somebody might want to read one (first rule of book talks for librarians, in fact--one of the things I learned in grad school was how to make a book sound kind of interesting without giving anything vital away). But I have to say something about the ending here, and I think the spoiler statute of limitations on this one ran out long ago.
So here's the thing. I have read a lot of science fiction over the years, and I am also really fond of historical novels, so both sides of this story appealed to me. I have also read a lot of 19th-century novels, so I'm not put off by a leisurely pace. So far, so good; I really enjoyed the story.
But then the author drops a variation of the venerable Grandfather Paradox (TV Tropes link, click with caution) on the very last page, and the narrator just walks away from it without considering the implications at all. Here's the spoiler, if you're interested: he prevents the birth of the scientist who will be in charge of the time travel project in the 1970s, which should have prevented the project and made his own presence in 1882 impossible, and then he just walks away. It drove me nuts, though I couldn't get across to my book club just why I found that so infuriating.
So maybe it's just me.