The 37th hour - Jodi Compton

Sarah Pribek is a police officer in the Missing Persons department. She, of all people, knows that the first 36 hours in a missing persons case are the most crucial. When she learns that her husband Shiloh has failed to show up for FBI training in Quantico, Sarah commences a Missing Persons search for her own husband. But already it's the 37th hour.

The search takes her to his family where she hears of a sister she never knew he had, to New Mexico, where (coincidentally?) she grew up, and finally back to her ex police partner, Genevieve, where all the threads of this brilliantly told novel come together.