Buck,apowerfuldog,halfSt.Bernardandhalfsheepdog,livesonJudgeMiller¡¯sestateinCalifornia¡¯sSantaClaraValley.Heleadsacomfortablelifethere,butitcomestoanendwhenmendiscovergoldintheKlondikeregionofCanadaandagreatdemandarisesforstrongdogstopullsleds.BuckiskidnappedbyagardenerontheMillerestateandsoldtodogtraders,whoteachBucktoobeybybeatinghimwithacluband,subsequently,shiphimnorthtotheKlondike.ArrivinginthechillyNorth,Buckisamazedbythecrueltyheseesaroundhim.Assoonasanotherdogfromhisship,Curly,getsofftheboat,apackofhuskiesviolentlyattacksandkillsher.Watchingherdeath,Buckvowsnevertoletthesamefatebefallhim.BuckbecomesthepropertyofFrancoisandPerrault,twomailcarriersworkingfortheCanadiangovernment,andbeginstoadjusttolifeasasleddog.Herecoverstheinstinctsofhiswildancestors:helearnstofight,scavengeforfood,andsleepbeneaththesnowonwinternights.Atthesametime,hedevelopsafiercerivalrywithSpitz,theleaddogintheteam.Oneoftheirfightsisbrokenupwhenapackofwilddogsinvadesthecamp,butBuckbeginstoundercutSpitz¡¯sauthority,andeventuallythetwodogsbecomeinvolvedinamajorfight.BuckkillsSpitzandtakeshisplaceastheleaddog.WithBuckattheheadoftheteam,FrancoisandPerrault¡¯ssledmakesrecordtime.However,themensoonturntheteamovertoamailcarrierwhoforcesthedogstocarrymuchheavierloads.Inthemidstofaparticularlyarduoustrip,oneofthedogsbecomesill,andeventuallythedriverhastoshoothim.Attheendofthisjourney,thedogsareexhausted,andthemailcarriersellsthemtoagroupofAmericangoldhunters¡ªHal,Charles,andMercedes.Buck¡¯snewmastersareinexperiencedandoutofplaceinthewilderness.Theyoverloadthesled,beatthedogs,andplanpoorly.Halfwaythroughtheirjourney,theybegintorunoutoffood.Whilethehumansbicker,thedogsbegintostarve,andtheweakeranimalssoondie.Ofanoriginalteamoffourteen,onlyfivearestillalivewhentheylimpintoJohnThornton¡¯scamp,stillsomedistancefromtheirdestination.Thorntonwarnsthemthattheiceoverwhichtheyaretravelingismeltingandthattheymayfallthroughit.Haldismissesthesewarningsandtriestogetgoingimmediately.Theotherdogsbegintomove,butBuckrefuses.WhenHalbeginstobeathim,Thorntonintervenes,knockingaknifefromHal¡¯shandandcuttingBuckloose.HalcursesThorntonandstartsthesledagain,butbeforetheyhavegoneaquarterofamile,theicebreaksopen,swallowingboththehumansandthedogs.ThorntonbecomesBuck¡¯smaster,andBuck¡¯sdevotiontohimistotal.HesavesThorntonfromdrowninginariver,attacksamanwhotriestostartafightwithThorntoninabar,and,mostremarkably,winsa$1,600wagerforhisnewmasterbypullingasledcarryingathousand-poundload.ButBuck¡¯sloveforThorntonismixedwithagrowingattractiontothewild,andhefeelsasifheisbeingcalledawayfromcivilizationandintothewilderness.ThisfeelinggrowsstrongerwhenheaccompaniesThorntonandhisfriendsinsearchofalostminehiddendeepintheCanadianforest.Whilethemensearchforgold,Buckrangesfarafield,befriendingwolvesandhuntingbearsandmoose.HealwaysreturnstoThorntonintheend,until,oneday,hecomesbacktocamptofindthatYeehatIndianshaveattackedandkilledhismaster.BuckattackstheIndians,killingseveralandscatteringtherest,andthenheadsoffintothewild,wherehebecomestheleaderofapackofwolves.Hebecomesalegendaryfigure,aGhostDog,fatheringcountlesscubsandinspiringfearintheYeehats¡ªbuteveryyearhereturnstotheplacewhereThorntondied,tomournhismasterbeforereturningtohislifeinthewild.