隋炀帝（刘丹饰）荒淫无道，不理朝政，还听信谣言，诛杀李姓大臣，以致天怒人怨，百姓受苦，群雄四起抗暴。炀帝的表弟李渊（鲍汉琳饰）本对朝廷忠心耿耿，并因身分而坚拒叛隋，但因为炀帝一次试探，李渊终在次子李世民（冯淬帆饰）的设计力劝下，答应出兵起义；炀帝大惊，为了保命而起驾到江都。

在世民率领下，李渊义兵势如破竹，攻入长安，而炀帝在江都为叛将所弑，李渊遂在世民等人力劝下，即位长安，改国号唐，并立长子李建成（焦雄饰）为太子，世民为秦王。此时天下尚未平定，世民东征西讨，在李靖（何文汇饰）、红拂女（焦姣饰）等良将辅佐下，扫平群雄，立下不少汗马功劳。随着世民功高权大，声望日隆，天下归心，建成深感威胁，与世民的隔阂日深，甚至为保太子之位，要置世民于死地。

In ancient China, Emperor Yang is a tyrant who executes his ministers and neglects his people. Li Yuan, his loyal cousin, refuses to rebel against him until Emperor Yang's actions become unbearable. Li's son, Li Shimin, advises his father to raise an army against the emperor. After a successful revolt, Li Shimin becomes the Crown Prince of the new Tang Dynasty. As Li Shimin becomes more powerful, his relationship with his older brother, Li Jiancheng, deteriorates, leading to a deadly conflict.