Lost Without You by Ava Olsen

Rachel Desoumas’s father disappeared thirty-four years ago and never returned. A linguistics professor, Rachel excels at solving puzzles, but her father’s case is one she can’t solve alone. Enter Ethan Blackwell, former FBI agent, author and consultant. Partnering with Ethan is a smart move but falling for him is a risk Rachel isn’t sure she’s prepared for…
Ethan’s moved on from his FBI past. Or so he thought. When he gets a request from Rachel, he can’t resist. Not the mystery, and not Rachel…
From San Francisco to New York City, they’re hot on the trail of a very cold case and it’s not just the investigation that’s heating up. But Ethan’s plagued by an angry ex and Rachel’s desire for answers may prove costly.
As Ethan and Rachel journey closer to the truth, only one thing is clear: they’d be lost without each other.