Since her arrival at Dover Academy, the one person Kat has been able to depend on is her best friend Mee-Seen, better known as Mouse. But when Mouse gets a crush on the new art teacher, a misunderstanding comes between the two friends -- and a class trip to the art museum only makes it worse! When a famous painting is stolen right under their noses, will Kat and Mouse be able to smooth things out in time to catch the thief?