Bart Bromley (Tye Sheridan) is a hotel night clerk with Asperger's who hides cameras in guest rooms in order to observe and mimic normal behavior. One night he witnesses a woman named Karen (Jacque Gray) being murdered by her boyfriend. Bart is reluctant to show the footage to the police because of his own illegal activity, and his odd behavior makes detective Johnny Espada (John Leguizamo) suspect he did it. While the police investigate, Bart is transferred to a smaller hotel in the same chain, where he falls in love with the guest Andrea Rivera (Ana de Armas).
The Night Clerk contains examples of:
- Alliterative Name: Bart Bromley.
- Basement-Dweller: Bart still lives with his mother Ethel (Helen Hunt).
- Big Bad: Detective Nick, Karen's abusive husband who killed her and spends the rest of the film attempting to frame Bart for it.
- Big "NO!": Bart yells "NOOOO!" as he drives to the hotel where Andrea is being beaten by the killer.
- Bitch in Sheep's Clothing: Andrea acts kindly and even flirtatious towards Bart, but her ultimate goal is to frame him for Karen's murder.
- Character Tics: Bart sometimes shakes his hands, especially when he walks or runs.
- Clear My Name: Bart begins to investigate Karen's murder himself in order to clear his name, when he becomes the police's prime suspect. He succeeds when he leaves evidence to Detective Espada that incriminates Detective Nick and Andrea.
- Dirty Cop: Detective Nick, Karen's husband, turns out to be her killer and used his police connections to try to get Bart framed for the murder.
- Domestic Abuse: Karen's killer beats her before he shoots her. He also beats his mistress Andrea, and leaves her alive with a busted lip.
- Emasculated Cuckold: Bart is extremely upset and heartbroken when he sees Andrea having sex with another man.
- Femme Fatale: Turns out Andrea didn't come to Bart's hotel by happenstance. She deliberately went there by Nick's request to befriend and seduce Bart so she could frame him for Karen's murder.
- Hand-or-Object Underwear: Bart walks into the pool area while Andrea is swimming topless. When she sees him, she covers her breasts with her hands.
- Hates Being Touched: Bart is okay with being touched on the hair or through clothing, but not on his skin. When a barber accidentally touches his neck, he leaps out of the seat.
- The Heavy: While detective Nick is the instigator of the plot, having killed Karen and sent Andrea to Bart, he ultimately has very little presence in the movie; it's Femme Fatale Andrea who's treated as the main antagonist and the one with a personal relationship with Bart.
- Inspector Javert: Bart's attempts to hide his illegal cameras from the police coupled with his awkward social behavior makes him look suspicious to detective Espada, who starts to consider him a prime suspect in Karen's murder.
- Mama Bear: Ethel protects Bart from being harassed by the police when they don't have solid evidence. Even when Espada obtains a search warrant, she tries to stop him from touching Bart's things.
- Minor Crime Reveals Major Plot: Averted. Karen's assault and murder inadvertently put Bart and his illegal cameras on the police's notice, and his attempts to hide his minor crime only make him look more suspicious, which causes him to be considered a prime suspect in Karen's murder.
- The Mistress: Andrea has been having an affair with Nick for a long time, even while knowing he was married to Karen.
- Ms. Fanservice: Andrea is a Head-Turning Beauty who dresses and acts seductively in most of her scenes, and gets a fairly gratuitous Skinny Dipping scene where she's topless.
- Naked Freak-Out: While Andrea is Skinny Dipping at night, Bart walks up to the pool to talk to her. She doesn't notice him until she's climbing out of the pool right in front of him, and freaks out, covering herself with her hands. He hands her a Modesty Towel, but she's still peeved and asks him to turn around while she puts on a robe.
- "No Peeking!" Request: After he caught her Skinny Dipping, Andrea asks Bart to keep his back turned while she changes from a Modesty Towel into a bathrobe.
- The Peeping Tom: Bart claims his motives for spying on people are nonsexual, which doesn't stop him from directing attractive women to the rooms where he's hidden his cameras.
- Rage Against the Reflection: Bart ends up shooting one of the monitors in despair after he finds out Andrea set him up.
- Sexy Shirt Switch: When Bart visits Andrea's hotel one morning to ask her out, he can see her in the window answering the phone wearing only a man's shirt. Soon after the owner of said shirt sneaks behind her and starts to kiss her, and she dismisses the phone call.
- Sexy Surfacing Shot: There's a shot of Andrea climbing out of the pool topless, only for her to be startled when she finds Bart standing right there, and she freaks out and dives back into the water.
- Tattooed Crook: The only identifiably thing Bart can see in his recordings of the man who assaulted Karen is a tattoo of a bird on his arm.
- Too Unhappy to Be Hungry: Once the police discover Bart's footprints in the room (their first piece of solid evidence that he killed Karen) and he sees Andrea having sex with another man, Bart is so upset that he stays in bed and misses dinner. Ethel gives him a pep talk, reminding him of how much it hurt after his father died, and how they managed to survive anyway. She succeeds in convincing Bart to eat.
