Sightless

Ellen discovers the apartment was entirely fake, a soundproof room constructed to trap her. The windows with different sounds were actually speakers playing recorded traffic noise. This elaborate setup explains why Clayton always seemed to be present and why no one else could verify her fears about Lana being in danger.

Earlier, Ellen notices one window has thicker glass and hears a voice through the vent, clues that hint the apartment isn't real.

Clayton, the nurse hired to care for Ellen, is the kidnapper. He orchestrated the entire scheme, creating a fake apartment and playing multiple roles, including the detective, paramedic, and Russo, to manipulate Ellen into trusting him while keeping her trapped.

Clayton is conveniently always present and dismisses Ellen's concerns about danger, while hinting at romantic feelings.

Clayton was kept captive in his father's basement for three years after his mother's death. He became obsessed with Ellen after hearing her play violin through recordings made by his sister Lana. He believed he understood her and wanted to keep her trapped so she could only play for him.

Lana's recordings of Ellen's violin playing are mentioned early, and Clayton's hints about understanding Ellen's trauma foreshadow his own history.

Detective Bryce lies to Ellen, telling her that Sasha, her friend involved with her ex-husband, is the prime suspect in the assault. This is a deliberate manipulation to make Ellen doubt her friends and become more isolated and dependent on Clayton, who was controlling the investigation.

Detective Bryce reassures Ellen that no one entered the apartment after Clayton left, establishing Clayton's control over the narrative.

The vent served two purposes: first, it transmitted Lana's distressed voice to make Ellen believe there was a neighbor in danger, reinforcing the fake apartment's illusion. Later, Ellen uses the hidden vent behind Clayton's room to attempt escape, discovering it leads toward freedom.

Ellen initially hears voices through the vent and later finds a sticky note she wrote on a door that never opened, hinting the space was constructed.

The same chemical compound used to blind Ellen during the parking lot attack is later used by Clayton to try to control her again. Ellen discovers a vial of this substance during her escape and sprays it into Clayton's face, temporarily disabling him and allowing her to flee.

The attacker's breathing pattern that Ellen remembers from the parking lot matches Clayton's breathing, establishing his presence.

Lana is Clayton's sister who helped him kidnap Ellen. She was the one who recorded Ellen playing violin, which fueled Clayton's obsession. She initially appears frightened and abused to manipulate Ellen's sympathy, but ultimately helps Ellen escape when Clayton is disabled.

Lana's warning 'trust no one' and her fear of Russo set up her later role as both accomplice and reluctant rescuer.

Clayton was the original attacker in the parking lot who blinded Ellen. She recognizes his breathing pattern when he returns as the masked intruder, confirming he was the one who originally assaulted her, not Sasha or anyone else.

Ellen notes the intruder's breathing matches the attacker from the parking lot, but Clayton's manipulation makes her doubt her own perceptions.

Yes, Ellen escapes the facility by using the hidden vent, spraying the blinding substance into Clayton's face to disable him, and following Lana to an exit. Six months later, she has recovered and returns to performing violin on stage, having reclaimed her independence and artistic life.

Ellen writes letters to her loved ones before attempting suicide, but then fights back, signaling her determination to survive.

Clayton played multiple characters to manipulate Ellen: he was her nurse, the fake Detective Bryce, the paramedic who revived her, and even Russo threatening her in the hallway. This gaslighting made Ellen question her sanity and prevented her from identifying the real threat.

Clayton dismisses Ellen's concerns about Lana and Russo, while conveniently being present for every 'investigation' of her claims.