Amelia, a widowed orderly, has raised her 6 year old son Samuel alone after her husband Oskar was decapitated in an accident driving Amelia (who was in labour) to the hospital. Sam begins displaying erratic behavior: he rarely sleeps through the night and is preoccupied with an imaginary monster, which he has built weapons to fight. Amelia is forced to take her son out of school due to his behavioural problems.