The nation’s honour is at stake as the sneaky businessman Bang Johansen is planning to sell his biggest invention and state secret ever, the oil optimizing machine, for the highest bidder. But Egon Olsen has a plan. He and the rest of The Olsen Gang set out to obstruct the deal in order to save the nation and of course more importantly score the millions for themselves. All they need is a cooling bag, an umbrella, a slingshot and two pieces of chewing gum.