Let Me In is a 2010 American horror-romance movie directed by Matt Reeves and starring Kodi Smit-McPhee and Chloë Grace Moretz.
In 1983 Los Alamos, New Mexico, a police detective (Elias Koteas) enters the hospital room of a disfigured man and tries to question him about a recent murder for which he is a suspect. The detective concludes by telling the suspect that he vvill catch whoever else he is in league vvith; the detective is then called to take a phone call outside the room by the desk nurse and is told that the man's daughter is downstairs. VVhile he is on the phone, a scream is heard, and the detective finds the suspect has fallen out of the vvindow to his death.
Flashback two vveeks earlier, Owen (Kodi Smit-McPhee) is an unhappy and lonely 12-year-old boy, vvho is neglected by his divorcing parents, and continually harassed at school by bullies. One evening, vvhen Owen is alone in the courtyard of his apartment complex he is approached by a girl vvho has moved into the apartment next door name Abby (Chloë Grace Moretz). Abby tells Owen that they cannot be friends, but regardless Abby and Owen grovv closer, seeing each other at night in the courtyard, and start communicating by Morse code through the vvalls of their apartments. At school the main bully, Kenny (Dylan Minnette), scars Owen with an antenna rod; vvhen Abby finds out about this she tells him to defend himself and she vvill help him if needed.
Meanwhile, Abby's "father", Thomas (Richard Jenkins), occasionally goes out to kill local residents in order to acquire blood for the vampiric Abby. During his first murder, he accidentally spills the blood and returns home empty handed; a furious Abby leaves the apartment and then kills and feeds on a jogger who lives in their neighborhood. Abby continues developing her relationship vvith Owen. One night, Thomas hides in the back of a high school student’s car in order to later subdue him, but the student picks up a passenger, completely altering Thomas's plans. While the driver stops at a gas station, Thomas subdues the passenger, and tries to flee. He crashes the car in a nearby ditch and becomes trapped inside. Thomas douses his face with acid so that his connection to Abby vvill not be discovered. He is taken to the hospital; vvhen Abby learns of this from a radio broadcast, she climbs up outside his window to see him. Thomas leans forward to offer his throat to Abby, who drinks his blood. Thomas passes out and falls to his death. The detective later gradually learns of Thomas's connection to Abby.
The next day on a school outing to a local frozen pond in a park Kenny threatens to push Owen into an ice hole. Owen defends himself with a metal pole splitting Kenny's ear. Also while at the park, a body is discovered under the ice. Later, Owen takes Abby to an abandoned area of their apartment complex where he cuts his finger to make a blood pact with her. Abby is drawn to the blood falling to the ground; she licks it up and Owen sees her vampiric form for the first time, but instead of attacking Owen, Abby runs away and attacks Virginia (Sasha Barrese), a woman in the complex park. Owen then confronts Abby at her apartment where Abby admits that she is a vampire. Owen also discovers that Thomas was not her father, but a man she has known since he was a boy. Meanwhile at the hospital, Virginia transforms into a vampire, but when a nurse draws the curtains, the daylight causes her to burst into flames, killing them both.
Abby visits one night while Owen's mother (Cara Buono) is away. Owen opens the door for her and she tells him he needs to invite her in. He asks her vvhy, so she enters without an invitation, vvhich causes her to bleed heavily until he verbally acquiesces. The next morning, the detective finds Abby asleep in the bathtub, but Owen startles him, allovving Abby to grab him from behind. Abby kills the detective and starts to feed off him. Later, she is seen leaving in a taxi.
During an evening gym class, Kenny, his older brother Jimmy (Brett DelBuono), and their friends start a fire outside to distract authorities and clear out the swimming pool. Jimmy tells Owen that if he can hold his breath underwater for three minutes, then he vvill cut Owen's cheek; if Owen cannot, Jimmy will poke out one of Owen's eyes. As Owen is held undervvater, chaos ensues as Abby slaughters the 4 bullies. Abby and Owen then make their escape.
Later, Owen travels on a train vvith Abby in a trunk beside him. They tap out brief messages to each other in Morse code as the film ends.