Inzenity's "The Sense of the Sleight of Hand Man"
A classic-era Call of Cthulhu campaign set in the terrifying worlds of H.P. Lovecraft’s Dreamlands.
New York City is a city of vices. The year is 1925 and it is the height of Prohibition, but the flow of drugs and liquor continues unhindered, through darker corridors, in darker hands. For the few who can afford it, opium is the drug of choice. Very few can afford it for very long.
The characters have fallen behind on their payments to their supplier of opiates, Mr. Lao. He has shown his displeasure with polite threats and demonstrations of what his men, the Tongs, will do if he does not receive his money. These demonstrations involved swords.
take a look at the campaign wiki. There is some more helpful info there.