Twelve-year-old Katie now knows her neighbor Madeline is also the Mousetress, the city's most feared villain (or most misunderstood superhero), and she is ready to become the super sidekick she always wanted to be.

"Beak loves the snow, but his hopes are dashed when Ally informs him the swamp stays warm year-round and not much changes. As a matter of fact, the only big change is that it gets a lot more crowded! Beak soon discovers what Ally means when the snow birds arrive... Hawaiian shirt-wearing, music-jamming new neighbors who have flown south for the winter. At first, Beak is thrilled when they decide to spend their vacation in hiis tree--he loves to party!...