The Plumber

A stranger enters the building and randomly selects the ninth-floor button. He knocks on the Cowpers' door and introduces himself as Max, the building's plumber. Jill immediately notes they did not call for service, and Max remains affable and convincing.

Jill tells Max they didn't request a plumber, but he insists that it's a mandatory pipe check for the whole building. He is earnest and unruffled, trying to ease her concerns. He proceeds inside to begin his work.

Max starts chipping away at the tile under the sink, creating a growing mess in the bathroom. Jill rushes in to see what he is doing, and Max tells her to leave him to his work. He closes the door, then shocks her by taking a very loud shower right after.

Brian receives word that a team from the World Health Organization will interview him about his work. He rings Jill to share the news and dismisses her concerns about Max as overprotective.

Max tells Jill that the apartment pipes are a mess and promises to return the next day to replace them. His casual certainty contrasts with Jill's unease.

Max reiterates his presence by claiming he unlocked the door and was bringing in groceries, fueling Jill's suspicion. The pattern of odd, slightly ominous behavior continues as he finds excuses to visit the unit.

Max waits in his car for Brian to leave before heading up to the apartment, indicating he is watching and timing his visits. This patience underscores a growing menace behind the routine plumbing work.

Max erects an elaborate scaffolding apparatus in the bathroom, rendering it largely unusable and heightening the sense of intrusion. The construction complicates everyday life for the Cowpers and signals a peak in Max's interference.

During the dinner with the WHO officials, one guest becomes trapped in the rigging and injures himself. The incident triggers chaos and deepens the strain between Jill and Brian as the threat of Max becomes more real.

In an argument with Jill, Max promises to finish his work but warns he might rush the job, suggesting a haphazard approach. His menace underscores the danger of the building work spiraling out of control.

The plumbing explodes, flooding the bathroom with fetid water and forcing Max to reappear in the apartment. The scale of the damage confirms Jill's suspicions that Max is dangerous.

Police arrest Max; their search of his car uncovers items belonging to Jill that she had planted there to frame him. From the balcony, Jill watches as Max shouts that she set him up, sealing the dramatic turn of the investigation.