Emma Woodhouse arrives home in Norfolk ready to embark on adult life. Not only has her sister, Isabella, been whisked away on a motorcycle up to London, but her astute governess, Miss Taylor is at a loose end, abandoned in the giant family pile, Hartfield, alongside Emma's anxiety-ridden father. Someone is needed to rule the roost and young Emma is more than happy to oblige. But there is only one person who can play with Emma's indestructible confidence,...

"Even though her family calls her Emma Bemma, Emma knows she is really just Medium. That's because she's the middle kid between her two brothers, who everyone calls Big and Little. Big thinks he's the coolest kid on the planet now that he's 10. And everyone thinks Little is just adorable even when he picks his nose and eats it! What if she could get out of being the middle by taking on a new role? What if she acted BIG? Or even bigger than that?"--...

Emma is eager to foster Mittens the cat, but she did not anticipate the chaos a cat can cause--but than Mittens disappears.