London, 1888, unfolds under the shadow of the Jack the Ripper killings as a weary research pathologist, Mr Slade [Jack Palance] arrives late at the home of the Harleys—Mr William Harley [Rhys Williams] and Mrs Helen Harley [Frances Bavier]—to rent a room and an attic for his work. Mrs Harley immediately notices something off about him: he twists portraits of actresses to the wall, claiming their eyes are on him, and he offers little explanation about the nature of his research, beyond insisting he works late hours. The city feels thick with fog and fear, and, curiously, his American accent stands out against the London setting with no clear reason.
Soon Lily Bonner [Constance Smith], a luminous stage star freshly returned from Paris, arrives to stay at the house. Slade leaves for the evening in an Ulster coat, carrying a small black bag, and crosses paths with Lily before her opening-night performance. The show itself reveals costumes that look out of time, adding to the air of unease without providing any rational explanation for their appearance. At the theatre, Lily’s old colleague Annie Rowley [Lilian Bond], who has fallen on hard times, slips backstage to visit but is murdered by the Ripper in a cruel echo of the city’s latest violence.
Inspector Paul Warwick [Byron Palmer] is on the trail, telling Lily that the suspect was seen in an Ulster coat and carrying a small black bag. The next morning, Warwick questions Lily again, while Slade offers unsettling, unorthodox opinions about the killer and predicts the police will never catch him. Mrs Harley’s suspicions intensify when a burning smell drifts from Slade’s attic, and she becomes convinced he is the killer when she discovers that Slade has burned the black bag. Yet Mr Harley remains skeptical, noting that he himself owns a small black bag and once saw a man with such a bag mobbed in the streets.
Lily finds herself drawn to Slade; he speaks of his mother—an actress who was beautiful and cruel, who both loved and despised her. He recounts her downfall: she behaved in an adulterous manner, his father drank, and she ended her life as a “woman of the streets,” dying on Whitechapel’s streets. Slade even shows Lily a photograph of his mother. Warwick then escorts Lily to the Black Museum, where Slade accompanies them, much to Warwick’s displeasure. Inside the museum, Slade dismisses the gruesome exhibits with biting humor, yet he fixates on the five portraits of the Ripper victims, again insisting that the police will never stop him.
That same night, another woman is murdered, and Slade is later seen washing his hands in the river. Lily awakens to find Slade burning more clothing, including his Ulster coat, which bears possible blood stains; he claims a solution spilled on it and insists the garment may be contaminated. Warwick checks Slade’s credentials at the University hospital and learns he is involved in research and works extremely late. Lily pleads with Slade to meet her backstage that evening, while Warwick investigates further, matching Slade’s right-thumbprint to one left at a crime scene with help from Mr Harley. A drawer in Slade’s room reveals a photograph of his mother, which Lily quickly exposes as a troubling clue; Warwick’s team realizes that Anne Lawrence—the first Ripper victim—appears in a picture at the museum, linking Slade’s fears and memories to the crimes.
As Slade moves through the city’s night of performances and alleys, his unease grows with every glance at Lily, and he lashes out in a desperate attempt to possess or silence her. He confronts Lily backstage, confessing an uncontrollable rage at the sight of other men admiring her, and pulls a knife in a frenzied moment. Lily fights back, and Slade escapes through a window as police close in. A relentless pursuit threads through Whitechapel’s streets, and Slade seems to vanish into the Thames, vanishing beneath the dark water. Yet the river’s murky surface conceals no body, and the film leaves open the chilling possibility that Slade may have escaped, leaving Lily, Warwick, and the Harleys to confront a killer who may still be at large.
