Legends has it that whoever wields the Dragon Slaying Saber and Heavenly Sword will rule the world. The story follows young hero Zhang Wuji and his adventures in the Jianghu, and his romantic entanglement with four ladies.
元朝末年,群雄纷起,武林动荡。江湖传闻,得到屠龙刀倚天剑者,可以成为武林至尊,号令天下,莫敢不从。一时间风云四起,引发了武林中对屠龙刀倚天剑的争夺,几段姻缘和孽缘也由此产生。武当派张翠山与天鹰教殷素素因屠龙刀相遇相恋,最后亦因屠龙刀被正派人士所逼迫,双双自尽。他们的儿子张无忌长大成人后,机缘巧合下练成了绝世武功“九阳神功”和“乾坤大挪移”,成为了明教教主。
张无忌与元朝郡主赵敏、峨嵋派周芷若、表妹殷离和婢女小昭都有着千丝万缕的爱意。然而,看似柔弱的周芷若,为了获取倚天剑屠龙刀的秘密,不惜伤害殷离,陷害赵敏。张无忌虽看清了周芷若真实面目,但还是对她恨不起来。其后,张无忌化解了武林种种恩怨,辞去教主之位,与赵敏寄迹蒙古