Leo Stazak is a small time con artist on the periphery of the mob and he decides to con Frank Nitti in a stock scam. Stazak is a fast talker and an expert liar who quickly gains Nitti's confidence. Soon, the big man has entrusted half a million dollars to Stazak who has been printing fake stock certificates. Ness is also on to Stazak's printer and it doesn't take long for Nitti to realize what is going on.

When a large supply of hair tonic is stolen, Ness and the Untouchables are concerned that it may be used as a base for illegal - and deadly - liquor. Soon after, the stuff starts to appear flavored with ginger jake, a popular patent medicine. The result is a permanent neurological disorder that was first seen in a major outbreak in Kansas City. The first victim in Chicago is Mary Kay Spencer, a 17 year old who drank the stuff while out on a date with her boyfriend. Working with public health officials, Ness tries to track down the source of the deadly hooch.