Mao's

Mao's is an opium den in 19th-century London.

History
and Dr. Bartley visit the Mao's after they found out that tell swords that the was used in a series of murders was owned by C. Ebenezer Burns. Burns tell them at he sold them to a person with sideburns like a man in the den. Eliza and Bartley starting then hount the man with sideburns. The cops were also at the Mao's and capture the man.