Undercurrent

This is an Apple Books audiobook narrated by a digital voice based on a human narrator.
TRAPPED AT SEA 

In an instant Kathryn Brooks's idyllic transatlantic cruise turns to terror. It's hard to believe someone has it out for her, yet chandeliers don't explode on their own—and her best friend has gone missing. But Secret Service agent Sam West vows to protect her as every corridor poses a threat and any stranger may be an assailant. With the ship's security providing little assistance, Kathryn puts her trust in Sam. Yet losing her own life is no longer her only fear. As she and Sam strive to stay a step ahead of the enemy, Kathryn worries that by caring for Sam…she's put a target on his back, as well.