Diana is the quiet, capable paid companion to the wealthy widow Mrs. Bantry. Traveling to the exclusive Swiss hotel, she leverages her easily overlooked social position to observe the glamorous guests around her. An avid bird-watcher and amateur photographer, she remains highly alert to the mounting tensions and strange occurrences in the isolated alpine environment.

Catherine is the beautiful, demure wife of an ambitious Conservative politician. Educated at elite finishing schools, she presents a flawless, polished facade of obedience to high society. Beneath her decorous exterior, she acutely perceives the cruelty and deception in her unhappy marriage and feels increasingly trapped by her circumstances.

Sylvia is a flamboyant Hollywood actress struggling with the pressures of a fading cinematic career. She deliberately cultivates a provocative, hyper-visible public persona that acts as psychological armor in a male-dominated world. She masks her sharp intelligence and deeper personal insecurities behind the flashy image of a cinematic bombshell.

Miss Marple is an elderly spinster from the quiet English village of St. Mary Mead, traveling as a guest of her friend Mrs. Bantry. She presents the perfect image of a dithering, frail old lady with a fondness for knitting. She uses this harmless archetype as social camouflage to ruthlessly analyze the moral transgressions of the people around her.

Anthony is a rising star in the Conservative political party and a decorated war hero. He relies on his handsome features, charisma, and patrician demeanor to advance his ambitions and marry into wealth. In private, he is deeply controlling, abusive, and manipulative, treating those around him as disposable tools for his own advancement.

Bruno is a large, unkempt racketeer who served alongside Anthony during World War II. He bears physical and psychological scars from his past, including a missing earlobe. Driven by desperation, greed, and a crippling sense of inadequacy, he remains trapped in a sordid life on the fringes of the black market.

Christophe introduces himself as a French police detective from the Paris Judiciaire vacationing at the hotel. He is charming, handsome, and projects an aura of capable authority. When a sudden snowstorm isolates the guests with a killer, he steps up to manage the crisis, attempting to bring order to a rapidly escalating situation.

Charlie is a disheveled, highly agitated medical student carrying a doctor's case. He stalks the Narracott couple around the resort, making cryptic threats and demanding attention. His desperate behavior and access to medical drugs immediately mark him as a volatile presence among the elite guests.

Mrs. Dolly Bantry is a wealthy, recently widowed woman seeking a glamorous escape in the Swiss Alps. She is talkative, sociable, and prone to jumping to dramatic conclusions. Her presence brings a touch of conventional high-society normalcy to the trip, though she quickly becomes distressed by the macabre events at the hotel.