Muriel is a 68-year-old widow from Baltimore embarking on a two-week European vacation. Having recently cashed in a lost lottery ticket worth nearly nine million dollars, she takes a step out of her comfort zone to travel, though she struggles with deep-seated insecurities about her age and weight. She possesses a sharp eye for detail, honed through her background doing surveillance work for a private investigator.

Danny is an exquisitely dressed and groomed man who introduces himself to Muriel as a professional stylist. Smooth and confident, he quickly volunteers to help her revamp her floral wardrobe with more sophisticated choices. He provides witty, blunt commentary while maintaining an air of mystery regarding his true motives for traveling and his constant proximity to Muriel.

Elinor is Muriel's best friend since the first grade. Slim, petite, and highly sociable, she serves as a vibrant contrast to Muriel's reserved nature. As a widow who has been married three times, Elinor remains socially adventurous and openly looks forward to finding romance during their vacation.

Pat is a wealthy, aristocratic passenger on the Seine river cruise who quickly befriends Muriel. She possesses an effortless sophistication and down-to-earth charm that Muriel deeply admires. Despite a physical condition that requires her to use a cane, she projects immense confidence and independence.

Allan is a suave, silver-haired gentleman and lawyer from Maryland. As an experienced traveler, he smoothly steps in to assist the flustered Muriel with her transatlantic journey. His charming demeanor, helpful advice, and lavish attention offer Muriel a flattering spark of romance.

Harold is Muriel's beloved late husband, who passed away ten years prior to the events of the story. He was a devoted, exemplary partner who provided Muriel with a stable, loving life for nearly forty years.

Marko is a tall, dark, and handsome man in his sixties who exudes luxury and elegance. He joins the river cruise alongside his sister, Pat, and quickly captures Elinor's attention. He is polite but somewhat reserved, focusing much of his charm directly on Elinor during group outings.

Paul is an attractive, well-groomed widower from Pennsylvania traveling on the Seine cruise. Sent on the trip by his children to cheer him up after his wife's passing, he strikes up a warm, flirtatious connection with Muriel.

Cece is a frankly honest Parisian fashion designer and friend of Danny Johnson. She takes charge of revamping Muriel's wardrobe, outfitting her in bold, stylish pieces meant to boost her confidence and physical presence.

Tess is a private investigator based in Baltimore. She serves as Muriel's former employer and trusted confidante, utilizing her professional resources to dig up background information when Muriel asks for her help from abroad.

Constance is a wealthy heiress who reportedly drowned in a boating accident in Switzerland years ago. According to research, she lost much of her fortune in bad investments, including a small museum on her estate that famously burned down.