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