宋末(mò )蒙古蒙哥大(dà )汗南下侵宋,途中遇到(dào )飞天(tiān )炮阻击身受重伤。后法王虽偷得飞(fēi )天炮(pào ),然蒙哥伤势加重,只得撤兵。返程中(zhōng )被忽(hū )必烈偷袭,逃入雪山。蒙哥感到命不(bú )久已(yǐ ),写下血书,传位尚年幼王子海都后(hòu )自尽(jìn )。大雪山中人马走散,飞(fēi )天炮和血书(shū )失踪(zōng ),海都逃出雪山后遇到(dào )受伤(shāng )的法王,原来(lái )他受到中原三大高手(shǒu )的袭(xí )击,他们一起(qǐ )返回雪山找寻其它队(duì )伍但(dàn )是雪山迷宫使他们放弃。与此同时(shí )三大(dà )高手也感无力进入雪山,将进雪山(shān )迷城(chéng )的地图分成三份交各人保存。法王(wáng )带着(zhe )海都勉强到达师弟银(yín )枪法王处,将(jiāng )海都(dōu )托付给师弟后毒发身(shēn )亡。海都从此身负(fù )夺回帝位的重任。