Special Agents Ty Grady and Zane Garrett are back on the job, settled into a personal and professional relationship built on fierce protectiveness and blistering passion. Now they're assigned to impersonate two members of an international smuggling ring—an out-and-proud married couple—on a Christmas cruise in the Caribbean. As their boss says, surely they'd rather kiss each other than be shot at, and he has no idea how right he is.