The Quiet

Dot (Camilla Belle) is a young, orphaned, deaf and mute teenager. After the death of her father, who had also been deaf, she is sent to live with her godparents and their daughter Nina (Elisha Cuthbert), with whom she used to be close friends. However, she soon learns the secrets her new family withhold from the rest of the world as well as from one another.
Nina constantly insults Dot every chance she gets, unhinged by her arrival. Dot blames herself for her father's death in a car accident, believing that if she had been with him, she could have warned him of the oncoming danger. Soon after arriving, Dot discovers an incestuous relationship between Nina and her father, Paul (Martin Donovan). Paul invited Dot to stay in an attempt to control himself, wishing he could end the sexual relationship between him and his daughter. He tries to tell his wife Olivia (Edie Falco) about his relationship with Nina, but is unable to bring himself to say it.
"Life sucks, Dot. I feel like I can tell you this. I feel like I can be honest because you can't hear. Or can you? Look at you, eating your sandwich like a piglet while I talk. Strangely comforting...
When I first met you, I mean when you first moved in, I hated you. I hated your face, your dumb blank stare. But now that I feel like I know you again that's all changed. It's so nice to know there's someone whose life sucks more than mine."


â The beginning of Nina's monologue to Dot.
After discovering that Dot is neither deaf nor mute, Nina pretends that she doesn't know the truth. For reasons of her own, Nina still pretends that Dot cannot tell anyone, and confides in Dot her plan to murder her father. Dot becomes aware of everything Nina and Paul do behind closed doors and even tries to help Nina avoid Paul's advances.
Dot is assigned to be lab partners with Connor (Shawn Ashmore), a star basketball player. Their partnership arouses jealousy in Michelle (Katy Mixon), Nina's loudmouthed best friend, who likes Connor. Connor is able to communicate well with Dot by lip-reading in order to work on their report, knowing that with a disability of his own (Attention Deficit Disorder) he needs to improve his grades to receive a basketball scholarship. He also becomes very attracted to Dot and confides to her about personal things in his life, believing she is unable to hear him. After confiding that he is a virgin, Dot undresses for him and he has sex with her.
Meanwhile, Nina confides in Dot that she is planning to kill her father, and then running away and becoming a stripper, believing she can become famous "like Courtney Love." Before the "Spring Fling" dance, Nina tells Paul that she is pregnant, and needs $1,000 for an abortion. However, once he discovers tampons in her purse, he realizes that she is lying and is only attempting to obtain the money to get away from home. As Dot begins to play "Moonlight Sonata" downstairs, Paul confronts Nina about her lie. Nina tries to explain, but Paul, distressed that his daughter wants to leave him, begins to physically abuse her. The abuse turns into a rape attempt. Dot recognizes what is going on upstairs, stops playing piano (although the sonata plays on), and heads upstairs. The music finally stops when Dot uses a piano wire to strangle Paul to death, screaming at him to leave Nina alone. All the while, Olivia remains downstairs, staring at the news in a pill-induced stupor. When Paul's body hits the ground, Nina starts screaming and cursing at Dot. Olivia comes upstairs and her only comment on being faced with Paul's body is to tell Dot that it's a miracle that she can hear.
The two girls go to the dance where Dot dances with Connor, then reveals to him that she is able to hear and talk. Connor calls her a psycho and storms away. Both girls bury Nina's dress, which has her father's blood on it. At this point, Nina questions Dot about pretending to be deaf and mute. Dot reveals that she wanted to be closer to her father so she wouldn't be alone after her mother's death. When the girls return home, Olivia has turned herself into the police and claims that she, not Dot, killed Paul in order to protect her daughter and atone for allowing the abuse. The film ends on a philosophical note as the two girls play piano together, freed from their fathers.

Question: How does Paul discover that Nina is not pregnant?