Seeking Mr. Wrong by Tamara Morgan

A fool-proof way to spice up any relationship:
1. Infiltrate a deadly ring of thieves, cons, and crooks.
2. Try to escape with your lives.

Penelope Blue used to be one of the best jewel thieves in New York City―but that was before falling in love with FBI poster boy Grant Emerson. Now she works at his side, helping her former enemy catch her past-life colleagues, and she couldn’t be happier.

If only Grant would remember to play by the rules.

Now he’s gone undercover on a cruise ship full of hardened criminals. To keep him safe, Penelope must pretend they’re nothing but strangers…while searching for an information broker desperately wanted by the FBI. While doing her darndest not to backslide and steal 20 million dollars’ worth of diamonds from beneath the noses of the criminal elite. It’s all Penelope can do to keep this mission afloat…

Good thing this cat burglar has plenty of lives to spare.