Bertil is a five-year-old who is looked after by an elderly woman while his parents are at work. One day, tiny Simon Small, who lives in the cellar, calls upon Bertil to help fight a rat twice his size. Bertil’s life dramatically changes as he shrinks into the size of tiny Simon and together they wage war against the rat. Bertil is a five-year-old who is looked after by an elderly woman while his parents are at work. One day, tiny Simon Small, who lives in the cellar, calls upon Bertil to help fight a rat twice his size. Bertil’s life dramatically changes as he shrinks into the size of tiny Simon and together they wage war against the rat.