We Have Hours Left Til Morning by Maren Chase

Emilia is a loyal employee of the Directory, a shadow organization that governs time travel. She’s content with her life—she excels at remaining anonymous, and she’s able to provide for her aging parents. But then a fellow agent, code name Ariel, tries to kill Emilia for a crime she hasn’t yet committed.

On her next mission, Emilia is sent back hundreds of years to ensure that a high-profile assassination occurs the way it’s supposed to. Rattled after the mission is only partially successful, Emilia flees and runs into Ariel once again. This time she takes no chances and kills him before he can attack her . . . despite the fact that he doesn’t fight back.

Death doesn’t mean much to time travelers, though, and Emilia runs into Ariel again and again. This Ariel is different, and Emilia can’t help but fall for him, all the while knowing that she is his murderer. But if either of them steps out of line, the timeline could collapse—and it won’t just be their love that’s doomed.