Time travel is now legal, and matchmaking agency Kairos lets clients travel through time in search of love.

Ada Blum has always been "an old soul." She's convinced that she was born at the wrong time, and after a series of break-ins at her apartment and threatening messages, she's determined to figure out where she really belongs. She thinks she wants to go to Regency England, meet her Mr. Darcy, and settle down. However, a disastrous date ends with Ada covered in rancid chicken stock and rethinking her plans.

She returns to The Kairos Agency and agrees to try an entirely different era. She travels to 1920s New York where she meets Henry Levison, a small-time hood. After yet another horrible experience, she's about to give up on the whole matchmaking, time traveling adventure when she bumps into her first love, Samson St. Laurent, a State Senator with whom she had an affair that resulted in a major PR scandal for him and ruined Ada's life.

Sam is on the run through time, trying to use his knowledge of the future to make a fortune. He says he wants to win Ada back, but she's not sure that he's entirely trustworthy. In some ways, she's drawn to Henry, and when she discovers that he is going to be murdered, she decides to go back and save his life by bringing him to the present day--even if it violates every single Kairos rule.

As Ada jumps back and forth from the present to the past, she'll have to decide where her heart truly lies and which man she wants in her future.