"Oskar is a bullied, lonely, teenage boy living with his mother on a housing estate at the edge of town, when a spate of sinister killings rocks the neighborhood. Eli is the young girl who has just moved in next door. She doesn't go to school and never leaves the flat by day. Sensing in each other a kindred spirit, the two become devoted friends. What Oskar doesn't know is that Eli has been a teenager for a very long time... Let the Right One In is...