The film unfolds with a brutal murder on Sunset Boulevard in Hollywood, where detective Chandler Manning and his newly hired assistant Street Wilkenson step into a case that seems to begin as a one‑off tragedy. As they investigate, a second prostitute is killed, and the medical examiner draws a chilling connection: the crimes mirror a pair of killings seven years earlier, the infamous Jack the Ripper murders from 1888 London. The shocking twist is that Manning, who previously believed he had unmasked the killer, now faces the terrifying realization that the wrong man may have paid for those past crimes with his life. On the personal front, Manning must contend with a wife who once attempted suicide and a daughter, Amanda, who blames him for the family rift and the circumstances that followed.
parallel to the detective’s case, a second narrative threads through the story: a couple rents out their guest house to a lodger who prefers absolute quiet because he is a writer. Ellen Bunting, the wife, becomes entangled with this mysterious lodger, Malcolm Slaight, who appears to be drawn to the secluded space and to Ellen herself. He is wary of interruptions, while Ellen finds herself increasingly drawn to him, staging small acts of domestic care—delivering breakfast, tea, and other near‑missed opportunities to be near him. Her husband Joe notices the absence of movement around the guest house and suspects that Ellen’s episodes of imagination may be resurfacing, yet Ellen’s growing fascination with Malcolm complicates the couple’s dynamics.
As the copycat killer resumes striking, two more murders occur, and a witness describes a man clad in a long black coat with a black bag. Manning discovers a garbage can near the crime scene marked with the word BATTY, and when he opens it, a pair of bloody underwear belonging to one of the victims emerges. Wilkenson suspects how Manning knew to check the can, but Manning points back to the pattern that emerged from the earlier murders and the evidence that connected them. Delving into the old case, Manning revisits the man he had arrested at the time and retrieves a letter that was written to him after the arrest, a move that draws scrutiny from others who fear Manning is losing touch with reality. The tense confrontation with the evidence clerk leads to a dramatic confrontation at the station.
Ellen’s obsession with Malcolm deepens even as she tries to keep their association hidden. She brings him meals and measures to stay near him, and a moment in the kitchen—where she hands him a pair of scissors as he asks for them—feels loaded with danger and unspoken meaning. The tension between Ellen and Joe escalates: the newspaper exposes a footprint linked to the case, and Ellen, aware of the possible connection, weighs her actions against her fear of exposure. Joe’s growing suspicion of Ellen’s supposed hallucinations pushes him to challenge the possibility that anyone is truly present in the guest house.
The investigation widens as Manning and Wilkenson pursue suspects who frequent the area of the killings, bringing them to the Bunting residence. Ellen acts with unusual briskness when the detectives request access to the guest house, and a search warrant is eventually obtained. In a turn of events, Manning is summoned to a meeting with the precinct captain and the mayor, who see the situation—coupled with Manning’s personal life—as a potential threat to his judgment. With Manning suspended, Wilkenson is left to carry the investigation forward, the mounting pressure leading the Captain to suspect Manning of both the original crimes and any new acts of violence tied to the killer’s spree. The Captain even believes Manning may be orchestrating or participating in the murders to prove his theory, a charge that puts Manning under a cloud of distrust and fear.
Meanwhile, Ellen’s actions around the guest house intensify. She enters the residence to wipe away any trace of Malcolm, accidentally triggering a cabinet to spill red liquid that looks like blood. Malcolm soon appears with a black bag, and Ellen, realizing the danger of his presence, pledges to protect him and insists that she will not reveal what she has seen. Joe, unaware of the full truth, finds the police’s visits unnerving and grows more unsettled.
With the search intensified, Manning seeks help from Wilkenson as another murder rocks the area, and the room narrows to one remaining victim before the killer could vanish. A breakthrough comes when they finally access the cabinet in the guest house and uncover maps and red ink traces. Suspicion shifts toward Manning as the Captain, the police, and even Wilkenson look at the new evidence with doubt. Manning is briefly cuffed, but a separate clue leads them to Amanda’s dorm, triggering a pivotal chase.
The narrative then shifts to Amanda Manning at college, followed by Manning and Wilkenson as they connect the dots between London’s historic Ripper murders and the current Hollywood killings. Two maps—one of London, one of Hollywood—mark the murders, and the new Hollywood mark appears exactly where Amanda’s dorm lies. Manning convinces Wilkenson to remove the cuffs, and the two rush to intercept Amanda as she leaves for a venue, only to be confronted by the killer in a dramatic chase that ends back at the Bunting home.
Inside the residence, Ellen stands in the living room with a long, curved knife as the officers sweep in. Joe lies badly injured, but alive, as the investigation closes in on Ellen. The film’s closing explains Ellen’s motive: she has developed schizophrenia stemming from the death of her baby at birth eight years earlier, a trauma that fractured her perception of reality and gave rise to a delusional life in which her imagined son and the lodger played central roles. The police and press accept this account, but Manning remains unconvinced, a thread left hanging as the final image shifts to Malcolm, who is shown seeking new lodgings in Santa Monica, suggesting the story may have more layers yet to be explored.
