JohnnyCasar(MickeyRooney)runsawayfromahomeforwaywardboys,tiredofbeingteasedaboutbeingshortandapoorathlete.HesoonfindsapairofrollerskatesandisbefriendedbyBrunoCrystal(RalphDumke),whoallowshimtowashdishesathiscafé,whileapriestwhorunsthehome,FatherO'Hara(PatO'Brien),secretlykeepsaneyeonhim.
Atravelingroller-skatingteamtakesaninterestinJohnnyafterheshowssomeaptitude.HeclasheswithMackMiller(GlenCorbett),acockychampion,andfallsforMaryReeves(BeverlyTyler),anothertopskater.JohnnyendsupfeaturedingrudgematchesagainstMiller,wheretheytaketurnsone-uppingoneanother.
Ashisfamegrows,JohnnybecomeseverybitasarrogantasMillerandmore.Lifetakesabadturnwhenheisdiagnosedwithpolio.Alongperiodofphysicaltherapyfollows,untilawheelchair-boundJohnnytriestogethislifebackontrack.