In the heart of London, in a world where mice lead lives parallel to humans, a small and brave mouse named Olivia Flaversham embarks on a desperate quest. Her father, a talented toy inventor, has been kidnapped by the feared criminal mouse, Basil, who has a sinister plan to steal the city’s jewels. Desperate to rescue him, Olivia seeks the help of a somewhat eccentric and slightly arrogant private detective, none other than the brilliant and clever Basil of Baker Street.
With the help of his friend, the clumsy but loyal Dr. Dawson, Basil sets off on an exciting adventure to track down the villain. Their path is filled with mysteries and dangers, from sinister alleyways to the luxury of high society mice, as they try to unmask their enemy's dark plans. As the investigation progresses, Basil realizes that Olivia's kidnapping is just a piece of a much larger puzzle threatening the peace of the entire mouse community. The fight to save an innocent and thwart the mischief of the evil Ratigan becomes a race against time, packed with unexpected twists, humor, and bravery. With cleverness and a little help from his friends, Basil confronts evil in a battle that will highlight the value of friendship and perseverance in a world where even the smallest can do great things.