宋末蒙古(gǔ )蒙哥(gē )大汗南下侵宋,途中遇(yù )到飞天炮阻(zǔ )击身受重伤。后法王虽偷得(dé )飞天炮,然蒙(méng )哥伤势加重,只得撤兵。返程(chéng )中被忽必烈(liè )偷袭,逃入雪山。蒙哥感到命(mìng )不久已,写下(xià )血书,传位尚年幼王子海都(dōu )后自尽。大雪(xuě )山中人马走散(sàn ),飞天炮和血(xuè )书失(shī )踪,海都逃出雪山后遇(yù )到受伤的法(fǎ )王,原(yuán )来他受到中原三大高(gāo )手的袭击,他(tā )们一(yī )起返回雪山找寻其它(tā )队伍但是雪(xuě )山迷宫使他们放弃。与此同(tóng )时三大高手(shǒu )也感无力进入雪山,将进雪(xuě )山迷城的地(dì )图分成三份交各人保存。法(fǎ )王带着海都(dōu )勉强到达师弟(dì )银枪法王处(chù ),将海都托付给师弟后毒发(fā )身亡。海都从(cóng )此身(shēn )负夺回帝位的重任。