In The Seductress 5, Millie and her sister Haley are leaving for a vacation to an exclusive resort in the Caribbean. Along for the trip are Haley's new boyfriend, Shawn, and Millie's new boyfriend, Nathan, who Haley has known since high school. Millie has always been a wild card who's been in and out of many relationships, but now she swears that Nathan is the only one. All is well until she becomes intrigued by a married man at the resort and starts to slip back into her old habits, leaving Haley with a choice: warn Nathan and ruin the trip, or hope that Millie comes to her senses in time.