Something is rotten at the Elsinore Brewery. Bob and Doug McKenzie (as seen on SCTV) help the orphan Pam regain the brewery founded by her recently-deceased father. But to do so, they must confront the suspicious Brewmeister Smith and two teams of vicious hockey players.
Two unemployed brothers, Bob and Doug McKenzie (Rick Moranis and Dave Thomas), place a live mouse in a beer bottle in an attempt to blackmail the local beer store into giving them free Elsinore beer, but are told to take up the matter with management at the Elsinore brewery. The brothers are given jobs on the bottling line inspecting for mice in the bottles.
Meanwhile, the evil Brewmeister Smith (Max von Sydow) is perfecting a secret plan to take over the world by placing a mind-control drug in Elsinore beer which, while rendering the consumer docile, also makes him or her attack others when certain musical tones are played. Smith tests this adulterated beer on patients of the neighbouring Royal Canadian Institute for the Mentally Insane, which is connected to the brewery by underground tunnels.
Bob and Doug learn that the brewery’s former owner, John Elsinore, has recently died under mysterious circumstances and his daughter Pam (Lynne Griffin) has been given full control of the Elsinore brewery. While exploring the massive brewery, they find a shuttered cafeteria containing an old Galactic Border Patrol video game which supernaturally reveals that Brewmeister Smith murdered John Elsinore and that Pam’s bumbling Uncle Claude (Paul Dooley) was deeply involved. Also, Bob recognizes a brewery employee as one-time hockey great Jean “Rosie” LeRose (Angus MacInnes), who suffered a career-ending nervous breakdown and has fallen under Smith’s control…