An Old Captivity, by Nevil Shute

Second paragraph of third chapter:

He said quietly at last: “I hadn’t reckoned on that. That makes it very difficult.”

A fascinating book by Shute. His usual competent engineer hero is tasked with organising an archaeologist’s air photography mission to Greenland, sponsored by the archaeologist’s rich elder brother, and to his dismay accompanied by the archaeologist’s daughter. The planning and implementation of the expedition are lovingly detailed; the year is roughly 1937 (the book was published in 1940, but there is no mention of impending war).

And then three quarters of the way through, we have a sudden shift; and our competent engineer hero falls into a coma and dreams of a past life as a Scottish slave among the Viking settlers of Greenland, with the professor’s daughter being his lover’s reincarnation. That part of the story told on its own could easily fall into total cliche, but the fact that we have had a couple of hundred pages of technical exposition beforehand makes it tremendously effective. A very pleasant surprise. Well worth getting.