Billy, Charlie, and Black Tom are three inseparable friends navigating life together in London's East End, a true den of thieves. Fortunately, the trio can count on the protection of a certain Sherlock Holmes, who occasionally hires them as street spies. However, when Black Tom's girlfriend is kidnapped right before their eyes, they must quickly put into action the tricks they learned from their mentor. Unexpectedly, they receive help from a fourth little rascal. Thus, the four from Baker Street are complete, forming the youngest detective team of the Victorian era.