A madman stalks the streets of London's Whitechapel slum, leaving a trail of grisly murders in his wake. The police have only one suspect: a prominent and respected physician named John Watson! The master detective Sherlock Holmes, in order to solve the most fantastic mystery of his career and save his greatest friend from the gallows, employs a band of young street urchins to infiltrate the alleys of Whitechapel. They can go everywhere, see everything, overhear everyone. They are the Baker Street Irregulars!