By Michael Flynn.
Science fiction set in the Middle Ages. (There is a present day component interspersed with the narrative from the 1300s, too, but it's not the largest part.) The best thing about this book is how real it seems; although I don't know much about the Middle Ages, the author has either done his research or is very good at faking it with realistic details. (For example: the Inquisition had very strict rules for trials, so much so that people were known to commit blasphemy so that they would be tried by the Church courts rather than the secular ones.) The writing is crisp, not vague. The intersection between two different cultures is also very interesting; what one insists at the beginning is true seems to change as they interact with each other.
The story, in short, is that an alien ship crashes in Eifelheim, a village in medieval Germany. The priest of that village becomes the mediator between the aliens and the villagers, trying to help and understand them while serving his own flock. In the present day segments, based on a novella, a historian and a physicist are about to stumble on what happened in that past, but the more interesting portion is the medieval narrative. Despite the sad ending (this is around the time of the Black Plague), the characters, both aliens and humans, have a great deal of pathos. It's especially interesting how the villagers, instead of being cardboard scenery, come to develop their own opinions about the aliens, who look nothing like men (they're described as giant grasshoppers), but inside are human, although foreign.
Recommended. As an aside, I would be interested in knowing if someone who actually does know about medieval Germany could comment on the factuality of the world-building.