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. Unfortunately, he also realizes that the park is under police surveillance and refuses to go through with the buy. When the drugs disappear, Frank Nitti makes it quite clear that he expects Justin to deliver the goods, or else.