A mouse in a yellow hat helps himself to what he thinks is a huge lump of cheese in a bakery but, after chewing a hole straight through it, realizes that it is really rum cake, which has made him more than a little drunk. The mouse staggers away, hiccupping. The next morning, he has a severe hangover, and sounds of drilling at a nearby construction site give him excruciating pain. He grabs the nearest piece of ice he can find to apply to his head, and again he has made a mistake. The ice is the Sunflame Diamond, and two policemen, one of them a lunkhead, are assigned to investigate the "theft" of the jewel. They bungle all their attempts to catch the mouse, who has the jewel tied to his head.