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