Undercover Marriage

This is an Apple Books audiobook narrated by a digital voice based on a human narrator.
THE BABY MISSION 

An illegal adoption ring—using kidnapped babies—has to be stopped. To gather the necessary evidence, U.S. marshal Serena Summers goes undercover—as a married woman desperate for a baby. Her "husband" is her own partner, U.S. marshal Josh McCall, whom Serena blames for her brother's death. How can she act like a loving wife when she has to constantly fight her feelings for a man she isn't sure she can trust? The closer they get to unraveling the dark web of deceit, though, the more being Josh's undercover wife means putting her life—and future—in his hands. 

Witness Protection: Hiding in plain sight