When Rosie finds a tiny tartan sock in her bedroom she's sure it could only fit one thing - a fairy! Mum tells Rosie not to be so silly, fairies don't exist.
Then the old lady who lives next door tells Rosie that Mum's the one who's silly, fairies are everywhere if you know how to look. And they love chocolate.
Rosie's not sure who to believe until she sees something in the grass at the top of the moor and then she can hardly believe her eyes. It's fluttering and tiny and magical. Could it really be a fairy . . . ?