Acting on an anonymous tip, Eliot Ness and his men find themselves at a local carnival keeping an eye on an impending purchase of narcotics. The seller is Alexander Rader, a known drug dealer and the buyer is Arnold Justin on behalf of Frank Nitti. They are scheduled to meet in an electrical room accessible only through the tunnel of horrors tide. Justin is an ex-Chief of Detectives who was always honest when on the force but decided he was fed up putting his life on the line for minimal pay so he quit and now acts as a buyer for the mob.

Matt Bass is an ex-con and a former member of Al Capone's criminal empire. In prison, a fellow con, engineer Jason Fiddler develops what he thinks is the perfect way to deliver illicit liquor to central Chicago. Once out of jail, Bass approaches his old friend Frank Nitti to sell the idea. Nitti has been hit hard lately by Eliot Ness and the Untouchables who have pretty well shut down most of his distilleries and the speakeasies are starting to close their doors. Nitti tries to solve the delivery problem himself but in the end, agrees to Bass and Fiddler's scheme. Ness is soon on to them however.