Ministry of Time by Kaliane Bradley

In the near future, a civil servant is offered the salary of her dreams and is, shortly afterward, told what project she'll be working on. A recently established government ministry is gathering “expats” from across history to establish whether time travel is feasible -- for the body, but also for the fabric of space-time. She is tasked with working as a “bridge”: living with, assisting, and monitoring the expat known as “1847” or Commander Graham Gore. As far as history is concerned, Commander Gore died on Sir John Franklin's doomed 1845 expedition to the Arctic, so he's a little disoriented to be living with an unmarried woman who regularly shows her calves, surrounded by outlandish concepts such as “washing machines,” “Spotify,” and “the collapse of the British Empire.” But with an appetite for discovery, a seven-a-day cigarette habit, and the support of a charming and chaotic cast of fellow expats, he soon adjusts. Over the next year, what the bridge initially thought would be, at best, a horrifically uncomfortable roommate dynamic, evolves into something much deeper. By the time the true shape of the Ministry's project comes to light, the bridge has fallen haphazardly, fervently in love, with consequences she never could have imagined. Forced to confront the choices that brought them together, the bridge must finally reckon with how -- and whether she believes -- what she does next can change the future.