宋末蒙古蒙哥大汗南下侵宋,途(tú )中遇(yù )到飞天炮阻击身受重伤。后法王虽(suī )偷得(dé )飞天炮,然蒙哥伤势加(jiā )重,只得撤兵(bīng )。返程(chéng )中被忽必烈偷袭,逃入(rù )雪山。蒙哥感(gǎn )到命(mìng )不久已,写下血书,传位(wèi )尚年(nián )幼王子海都(dōu )后自尽。大雪山中人马(mǎ )走散(sàn ),飞天炮和血书失踪,海都逃出雪山(shān )后遇(yù )到受伤的法王,原来他受到中原三(sān )大高(gāo )手的袭击,他们一起返回雪山找寻(xún )其它(tā )队伍但是雪山迷宫使他们放弃。与(yǔ )此同(tóng )时三大高手也感无力(lì )进入雪山,将(jiāng )进雪(xuě )山迷城的地图分成三(sān )份交各人保存。法(fǎ )王带着海都勉强到达(dá )师弟(dì )银枪法王处(chù ),将海都托付给师弟后(hòu )毒发(fā )身亡。海都从此身负夺回帝位的重(chóng )任。