Dark Latitude. A Lexi Balestra Mystery, #1

Lexi, a feisty millennial, finds her plans for a vacation after college shattered by the death of a friend and an echo from 1945. Everything changes when she becomes the target of an assailant and her conscience wrestles with her dead friend's activities during WWII. She transforms from victim to sleuth with the help of a protective FBI agent, and a savvy history professor with ties to the intelligence community.
Lexi's discovery of a mysterious airplane leads her and an FBI task force to groups of operatives who extended the reach of fascism across Central and South America after the war. Constant interaction between Lexi and the FBI agent leads to the beginning of a relationship. She maintains her distance, but it's game on.