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