AftervisitingMonstersInc.—Monstropolis'mostprofitableandbest-knownscaringcompany—onaschoolfieldtrip,ayoungmonsternamedMichael"Mike"Wazowskidreamsofbeingascarerwhenhegrowsup.Elevenyearslater,MikeisascaremajoratMonstersUniversity,wherehemeetshisnewroommate,Randall"Randy"Boggsandalarge,blue,furrymonsternamedJamesP."Sulley"Sullivan.

　　Mikestudieshard,whiletheprivilegedSulley—whocomesfromatalentedfamilyofscarers—reliesonhisnaturalscaringabilityandbeginstofalter.Atthefinalexam,MikeandSulley'srivalrymakesDeanHardscrabblefailthembothanddropthemfromtheprogram,promptingRoarOmegaRoartoremoveSulleyfromtheirteam.MikedecidestoprovehimselfbyenteringtheScareGamesbutOozmaKappa—theonlyfraternitythatwasremovedfromtheprogram—isdeniedentryastheyareoneteammembershort.Seeingthecompetitionashisticketbackintothescareprogram,SulleyjoinsandMikereluctantlyaccepts.

　　OozmaKappafailsthefirstchallenge,anobstaclecoursewherethecontestantsdodgeharmful,glowing"urchins",butmiraculouslyadvanceswhenanotherteamisdisqualifiedforusingprotectiongel,whichviolatestheScareGames'rules.ThecontestantsattendRoarOmegaRoar'spartywheretheothercompetitorshumiliateanddiscourageOozmaKappa.MikearrangesasecretvisittoMonsters,Inc.tolifttheirspirits,butSulleystilldoubtsthatMikecanbeatruescarer.Aftertheteamwinsthefinalround,MikediscoversthatSulleycheatedtoimproveMike'sscore.Determinedtoproveheiscapableofbecomingascarer,Mikebreaksintotheschool'sdoorlabandentersadoortothehumanworld,butthedoorleadstoasummercampandheisunabletoscareacabinfullofchildren.

　　Backattheuniversity,SulleyconfessestoHardscrabblethathecheated,justassheisnotifiedofthebreak-in.Realizingwhathappened,SulleyentersthedoortolookforMike.Afterfindingandreconcilingwithhim,theytrytoreturnbuttheyfindtheyaretrappedinthehumanworldbecauseHardscrabblehasdeactivatedthedoorwhilewaitingfortheauthoritiestoarrive.Mikerealizesthattheonlywaytogetbackintothemonsterworldistogenerateenoughscreamenergytopowerthedoorfromtheirside.

　　Workingtogether,SulleyandMiketerrifytheadults,generatinganoverwhelmingamountofscreamenergyandallowingthemtoreturntothelab.Theiractionsleadtotheirexpulsionfromtheuniversity,buttheothermembersofOozmaKappaareacceptedintothescareprogramthenextsemesterbecauseHardscrabbleisimpressedwiththeirperformanceinthegames.TheysharegoodbyesandasSulleyandMikeleave,Hardscrabbletellsthemtheyarethefirsttohavesurprisedherandwishesthemluckforthefuture.MikeandSulleybeginworkatMonsters,Inc.inthecompanymailroomunderthemailroommanager,theAbominableSnowman.Workingtheirwayupthroughthecompany,thetwoeventuallybecomepartoftheScarerTeam,thussettingtheeventsofMonsters,Inc.inmotion.

　　Reference:wikipedia