In New York City, Stuart Little, a small, courageous mouse adopted by the Little family, experiences a life filled with adventure and love. Despite the dangers he faces in the big world, his optimistic spirit and the support of his human parents and brother keep him going. One day, while Stuart is driving his tiny car through the city, he meets Margalo, a beautiful canary being pursued by a menacing falcon. He rescues her, and they quickly become the best of friends. Margalo is welcomed into the Little family, and Stuart finds himself deeply drawn to her, enjoying their shared moments and beginning to feel a kind of happiness he hadn't known before.

However, Margalo harbors a secret tied to the falcon that endangers not just her newfound family but also tests the bond she has formed with Stuart. As Stuart navigates the complexities of friendship and loyalty, he embarks on a quest that pushes him to the limits of his courage and determination. The challenges he faces on this journey not only test his physical abilities but also teach him valuable lessons about trust, betrayal, and the true meaning of friendship. His adventures take him across the city, encountering various obstacles and characters that help him grasp the importance of standing by those you love, no matter the risk.