Found Wanting — Joyce Lamb

Detective Mitch Kane is hired by millionaire Layton Keller to find his son and the woman who took the boy fourteen years ago.
But Mitch soon discovers that Alaina Chancellor isn't anything like he expected. Before he knows it, the boy has been kidnapped and Mitch is protecting Alaina from hit men while trying to help her get Jonah back.

But Alaina has been hurt before, and she doesn't trust anyone easily, especially a detective hired by her son's father.
Unfortunately, she has no choice but to rely on Mitch, and as they race to save Jonah, they discover that both their lives have been found wanting.