Maia and her best friend, who happens to be a monster,are both becoming big sisters. This is NOT good news! When Mom tells Maia their new baby will be her best friend, Maia is skeptical. Then Maia's baby and Monster's baby are born. Though they gurgle, growl, scream, and spit, they eventually win their way into their big sisters' hearts. Nonetheless,Maia and the Monster agree: "WE are the friends. THEY are the babies."