When 10-year-old Summer McKay calls a wrong number and finds herself talking to Emily Lear, the class blabbermouth, she becomes flustered and invites Emily to her upcoming slumber party. At the overnight Emily threatens to take over Summer's friends as well as the party. Without thinking, and in an effort to get the girls' attention, Summer lies and blurts out that her very common basset hound is an award winning show dog. To make matters worse, every time Summer thinks her boast is forgotten, Emily makes sure everyone remembers. Now, at the teacher's invitation, Summer has to bring her not-so-special dog to class, but what she'd really like to do is put a zipper on her big mouth and Emily's too-if she can stand to be around her that long.