The cartoon opens with a circus featuring "Gracie, the Fightin' Kangaroo!". Gracie has a baby (Hippety Hopper) while practicing, and isn't able to stay with him very long. While Gracie goes off to perform, Hippety slips on a pair of his mother's boxing gloves, and wanders off (along the way, treading in wet cement, much to the anger of the workman who is paving the new sidewalk, falling into a pink dress and causing several cars to crash).
Meanwhile, Sylvester is bragging to his son about how he took on a mouse about his own size. Unfortunately, Hippety shows up behind him, leading Sylvester into a panic. Junior urges Sylvester to fight Hippety, as they both think he's a giant mouse, and says that if he doesn't, he'll "disillusion a child's faith in his father." The result is a fight between Hippety and Sylvester. Hippety wins at first, but then Sylvester chases him off with an axe. Along the way, they pass the workman, who treads in his own cement as if daring the participants in the chase to do the same – but when they do not, he stands in the center of the sidewalk and plays "Taps" on a trumpet as he sinks.
Sylvester is led to the circus, and right when Junior enters his sight, he starts gloating again ("... and if I ever catch ya again, I'll give ya the same thing! Only THIS time, I'll break BOTH your legs, you giant mouse, you!"). After gloating, Sylvester says he wished Hippety was twice as big, with 4 arms and 2 heads. Ironically, Gracie comes out with Hippety in her pouch, causing both the cats to run off. Hippety gives them a friendly wave good-bye, and the cartoon closes.