The clues are in, the chase is on, and the case of the century is about to break wide open. On the cobblestone streets of 1897 London, some suspicious "mousechief" sets the scene for a thrilling musical adventure. Olivia, the brave daughter of a beloved toy maker, turns to Basil of Baker Street for help with her father's disappearance. Basil's jolly assistant, Dr. Dawson, and loyal dog Toby lend a paw - and nose - as they search for clues throughout their charming miniature world. The final chase leads to Professor Ratigan, a hard-hearted criminal. Can Basil outwit Ratigan to save Olivia's father and all of Mousedom?