Petunia the platypus heads to her first party since arriving from Australia. She has the present, a party hat, and a pavlova, but it's a costume party and she doesn't have a costume! Everyone asks what she's supposed to be: "Are you a duck?" "Do you have webbed feet?" "Can you lay eggs?" Even without a costume, Petunia stands out, and all of the other party guests give her a full-on identity crisis! Will she, with her weird quirks, ever fit in? ...