Rosie loves things that are red -- and especially she loves fire engines!Her home is next door to the Merrivale fire station, and every week she helps fire chief Hamish MacTavish polish the fire engine till it shines.
Rosie's billycart is painted to look like a miniature fire engine, but she's love a real one of her own. When Mum and Dad need to buy a new used car, she finds one in Col's Car Lot. It's just what she wants -- but her parents have different ideas. Rosie thinks this is unfair. So when it's time to go with Mum and Dad to the Merrivale picnic, Rosie decides not to go, and she persuades her best friend, Ned, not to go either.
While they are playing in the treehouse, they discover that there's a real fire in Hamish MacTavish's fire station -- and Hamish is away at the picnic! Now it's Rosie to the rescue.