The Girl Who Knew Too Much (1963)

In this suspenseful tale of mystery and danger, Nora Davis, a New York-based devotee of mystery novels, embarks on a journey to Rome to visit her ailing mother's friend, Ethel Windell Batocci. An innocent encounter on her flight leads her into the ominous world of drug dealing, setting an unsettling tone for her vacation. Upon her arrival, she finds Ethel on her deathbed and crosses paths with the enigmatic Dr. Marcello Bassi. The tranquility of Nora's life shatters when Ethel succumbs to a heart attack, and a terrifying incident leaves Nora unconscious on a staircase, where she awakens to a horrifying spectacle of a woman being brutally murdered. Despite her earnest pleas, her tale is met with skepticism at the hospital, leaving Nora to confront the chilling reality of her situation alone. At Ethel's funeral, Nora's solitude is broken by Laura Craven-Torrani, a stranger claiming to be an old friend of Ethel's. She offers Nora refuge in her apartment while she leaves for Switzerland, an invitation that Nora gratefully accepts. As she settles into her temporary abode, Nora's intrigue propels her to investigate the murder she witnessed, leading her to a heart-stopping revelation. She stumbles upon the disturbing pattern of the infamous Alphabet Killings, a series of murders that have haunted Rome for years and have stumped local law enforcement. As the pieces of the puzzle fall into place, Nora finds herself being targeted by the elusive killer. Simultaneously, the police see her as a crucial asset in their hunt for the murderer. Suddenly, Nora is plunged into a deadly game of cat and mouse with the Alphabet Killer, her life hanging in the balance as she strives to outwit her pursuer and aid the police in their pursuit of justice.

The Girl Who Knew Too Much is a horror movie featuring Letícia Román.

The Girl Who Knew Too Much is currently streaming for free (ad-supported) on Freevee, Plex, Plex Player and Tubi TV and it's also available on AMC+ Amazon Channel, Shudder and Shudder Amazon Channel.