Two years have passed since we last visited the Little family and much has changed. Stuart has blossomed and settled nicely into his new life. He goes to school (in his very own car), is very handy when it comes to building model airplanes and is proud of the fact he made the soccer team. He loves having a big brother, George and new baby sister, Martha with whom he can play. Even Snowbell, the curmudgeonly cat with an attitude, has warmed up to Stuart in his own way. All is well in the Little world, but even so, Stuart yearns for a friend of his own--someone like him. Driving home from school, Stuart hears a loud squawk and suddenly an injured bird falls out of the sky, landing in the passenger seat of his car. When she regains consciousness, the mysterious bird introduces herself as Margalo. Frightened, she tells Stuart she is being threatened by Falcon, a feared crime lord who terrorizes all creatures living Manhattan. When Stuart learns the Margalo doesn't have a place to live he insists she stay with the Littles. Mr. and Mrs. Little immediately accept Margalo and, much to Snowbell's chagrin, welcome her to stay as long as she wants. It's obvious for all to see that Stuart has a crush on the charming and beguiling bird who promises him adventure... but Margalo is hiding a dark secret and is not what she appears to be. When she mysteriously vanishes, the unlikely duo of Stuart and Snowbell set out on long journey to find her unlock the mystery. The furry duo has no idea where they are headed--all Stuart knows is he has to find Falcon's lair and get Margalo back.