The Old Street Market is a flea market in Tintin's home city, first portrayed in The Secret of the Unicorn. An alarming rise in the number of robberies was reported in The Secret of the Unicorn. Daring pickpockets were operating in the larger stores, the cinemas and street markets, like the Old Street Market. A well-organised gang was believed to be at work. The police were using their best men to put a stop to this public scandal. Thompson and Thomson were also used. Their idea was to keep their eyes on the Old Street Market where Tintin the same morning went walking. They wanted a little later, after a conversation with Tintin, buy a lot of walking sticks. If the seller says they have to pay seven shillings, says one of the two that his wallet was gone.