十二年前七万赤焰军被奸人所害导致全军覆没，冤死梅岭，只剩少帅林殊（张哲瀚 饰）侥幸生还。十二年后林殊改头换面化身“麒麟才子”梅长苏（胡歌 饰），建立江左盟，以“琅琊榜”第一才子的身份重返帝都。梅长苏背负血海深仇，暗中帮助昔日挚友靖王（王凯 饰）周旋于太子（高鑫 饰）与誉王（黄维德 饰）的斗争之中，同时又遇到了昔日未婚妻——云南王郡主穆霓凰（刘涛 饰）却不能相见。梅长苏以病弱之躯为昭雪冤案、为振兴河山，踏上了一条黑暗又惊心动魄的夺嫡之路。During the 4th century, war broke out between the feudal Northern Wei dynasty and Southern Liang dynasties, leading Liang's General Lin Xie to take his only child, the 19 year old Lin Shu, to battle. Unexpectedly, Lin Xie was framed by a political rival, causing the unjust deaths of seventy thousand Chiyan army soldiers, just after they drove off the hostile Wei forces. After barely escaping with his life, Lin Shu establishes the Jiangzuo Alliance with the help of Langya Hall and makes a name for himself as Mei Changsu, chief of the pugilistic world. Under the alias of Su Zhe, he returns to the capital of Liang 12 years on to overturn the injustices imposed on the Chiyan Army and secretly assist his friend the unfavored Prince Xiao Jingyan in his battle for the throne.