Lori Bancroft, Talia Balsam, has recently moved and stops by a small urban apartment building to inquire about a vacant unit. The landlord and building superintendent, Karl Gunther, an older German man, offers a courteous tour and mentions that the last tenant—a young woman—vanished without paying rent. As they walk, Gunther hides a disturbing ritual in plain sight, briefly exposing a masochistic impulse by placing his hand over an open stove-top flame, all while maintaining a facade of normalcy.
Gunther presents a chilling double life. By day he appears as a respectable figure, but by night he abducts and brutalizes his young female tenants, locking them in attic cages where he tortures and mutilates them. He removes their tongues and spares none, keeping them alive so he can “have someone to talk to.” The backstory deepens as we learn of his past as a physician who once practiced euthanasia, a vocation he betrays with a sense of shame after discovering that his own father—a Dachau concentration camp doctor—used similar justifications during human experiments. He tortures himself with self-harm and even plays Russian roulette, clinging to the idea that he might someday end his spree and finally find some moral resolution within himself.
The tension escalates when Josef Steiner, Kenneth Robert Shippy, arrives after years of searching Gunther out. Steiner reveals his own history as a former chief resident at a Buenos Aires hospital, where sixty-seven patients died under his care, including Steiner’s brother. He confronts Gunther with the Nazi past that haunts both of them, including a photograph of Gunther as a youth in a Hitler Youth uniform and a lineage that ties back to his father’s crimes against humanity. Steiner’s intent is to confront, or perhaps stop, Gunther, but he underestimates the traps Gunther controls from his apartment and the extent of Gunther’s god complex.
As Gunther’s surveillance and weaponized ventilation crawlspaces become weapons, he begins to claim life and death as a twisted form of power. Steiner makes a bold move to assassinate him, but is lured into Gunther’s domain and killed by one of the killer’s own devices. With Steiner gone, Gunther stands before a mirror in a faux SS uniform, declaring himself his own god, his own jury, and his own executioner—an unsettling moment that crystallizes his narcissistic delusion.
When Lori returns to her apartment, she confronts the aftermath: a refrigerator teeming with live rats and Steiner’s corpse in the tub, a swastika carved into Steiner’s forehead. Panic spreads as Gunther triggers a cascade of security measures, trapping the entire building and forcing Lori to run from door to door, discovering that many neighbors have met brutal fates. Desperate, she flees to Gunther’s attic hideout, where she discovers the last surviving female prisoner in a cage. With Gunther closing in, Lori uses a booby-trapped crawlspace to slip away, navigating a deadly maze as Gunther releases a swarm of rats into the vents.
Lori’s pursuit becomes a tense cat-and-mouse sequence that sends her circling back toward Gunther’s room. In a moments-filled chase, Gunther’s own mechanisms backfire, and he impales himself on a blade he set in motion, leaving Lori and the remaining captive to seize the chance to escape. They sprint toward the stairs and the promise of police assistance, but Gunther, relentless, pursues them with a knife. In a final struggle, Lori seizes Gunther’s revolver, squeezing the trigger in a desperate bid for safety. The weapon misfires multiple times before finally delivering a single, decisive shot. Karl Gunther meets his death with a blunt acceptance, muttering a final, fatal affirmation: > "so be it."
