Brain Damage

Dr. Morris Ackerman comes back to his apartment in New York City after a trip to a gourmet delicatessen, carrying animal brains meant for his pet parasite, Elmer. His wife, Martha, is excited about the meal and goes to feed Elmer in the bathroom.

Martha discovers that Elmer, the one-foot long blue-eyed parasite, has gone missing from the bathroom. In a panic, she and Morris search their apartment frantically, tearing it apart in the hopes of finding Elmer.

Meanwhile, the Ackermans' neighbor, Brian, is in bed struggling with a headache when his girlfriend, Barbara, tries to wake him for a concert. Brian suggests Barbara go with his roommate Mike instead, choosing to stay in bed.

After returning to sleep, Brian wakes up to find blood trickling down his neck. A vivid hallucination ensues, where he sees blue water flooding his room and a bright eye watching him, leading to a state of confusion and fear.

In a moment of desperation, Brian notices the parasite Elmer slithering up his back. Elmer promises to give Brian a euphoric sensation of light if he will take him outside, ultimately attaching himself to Brian’s neck.

Once Elmer punctures Brian's neck to inject a blue liquid into his brain, Brian experiences bright colors and euphoria while running through a car junkyard. Under the influence, he becomes unaware of a security guard nearby.

Elmer latches onto the security guard and burrows into his head, killing him instantly. Brian watches in shock and awe as Elmer consumes the guard's brain, marking the beginning of their dark journey.

At a restaurant, Barbara expresses concern for Brian’s erratic behavior. Despite his attempts to explain Elmer’s influence and his newfound sensations, the parasite bites him, compelling him to escape outside into an alley.

In the club Hell, after being led outside by a blonde woman, Brian succumbs to Elmer's desires once again, which results in the woman's death. Brian struggles with guilt and confusion as he realizes Elmer’s true nature.

Brian learns from Morris that Elmer is an ancient parasite known as Aylmer, having lived since the Crusades. This alarming revelation pushes Brian to consider his next steps as Elmer’s killings continue.

After packing his things, Brian rents a hotel room and continues his disturbing relationship with Elmer. The parasite confesses to killing the woman and warns Brian he needs to provide him with fresh brains to sustain their addiction.

As Brian struggles with withdrawal, he succumbs to Elmer's demands and enters a communal bathroom where another victim is brutally killed. Brian’s descent into madness intensifies as he participates in these horrific acts.

Back in the apartment, Mike confesses his feelings for Barbara, unaware of the lurking danger. When Brian overhears them and succumbs to Elmer's influence once more, he brings inevitable doom to Barbara.

Morris and Martha confronts Brian. In the chaos that follows, Elmer kills Martha, leading to Morris’ futile attempts to save her. The tragic events culminate as Brian holds a gun to himself in despair.

As police respond to the commotion, Brian, now fully transformed by Elmer’s influence, takes his own life. The shocking outcome leaves behind a scene of horror with police witnessing the aftermath in the apartment.