Amadscientistgrandfatherinventsagenetictransformationmachineandhis4yearoldgrandsonaccidentallyturnshisbodyintothatofa30yearoldman.BabyBobbyescapesandrunsaroundtownashissiblingstrytocatchhimbeforetheirparentsgetbackfromvacationANDbeforethebadguysgettohimfirst.Themachineisworthalotofmoneyandtheyonlyhaveadaybeforethemachinelosesitscapabilitiestochangebabybobbybackbbb