宋末蒙(méng )古蒙哥大汗南下侵宋,途中(zhōng )遇到(dào )飞天炮阻击身受重伤(shāng )。后法王虽偷(tōu )得飞(fēi )天炮,然蒙哥伤势加重(chóng ),只得撤兵。返(fǎn )程中(zhōng )被忽必烈偷袭,逃入雪(xuě )山。蒙哥感到(dào )命不(bú )久已,写下血书,传位尚(shàng )年幼王子海(hǎi )都后自尽。大雪山中人马走(zǒu )散,飞天炮和(hé )血书失踪,海都逃出雪山后(hòu )遇到受伤的(de )法王,原来他受到中原三大(dà )高手的袭击,他们一起返回(huí )雪山找寻其(qí )它队(duì )伍但是雪山迷宫使他(tā )们放弃。与此(cǐ )同时(shí )三大高手也感无力进(jìn )入雪山,将进(jìn )雪山(shān )迷城的地图分成三份(fèn )交各人保存(cún )。法王带着海都勉强到达师(shī )弟银枪法王(wáng )处,将海都托付给师弟后毒(dú )发身亡。海都(dōu )从此身负夺回帝位的重任(rèn )。