Set during the Joseon Dynasty, Iljimae acts as a useless gangster in the marketplace by day but at night he is a chivalrous robber who robs corrupt government officials to give to the poor. After each robbery he leaves behind a wooden branch from a plum tree at the site of the robbery to take responsibility for the robbery. Bong Soon is a hilarious girl with good martial art skills and lives as a swindler. She only loves Iljimae and sacrifices her whole life for him. Eun Chan is a doctor’s daughter and is good in nature and usually helps miserable people. She meets Iljimae once by chance, and their sweet love story begins. However, her love puts Iljimae in a dangerous situation because an Imperial Guard also loves her.

在一个梅花盛开的夜晚，年幼的谦在柜子里目睹父亲惨死。在月光下闪闪发亮的宝剑花纹，染上父亲鲜血的梅花都印在他的脑海里。那天以后，谦的生活被卷入凄惨坎坷的命运当中，他渐渐长大，成为名叫龙的市井无赖。

13年后，龙因为有人追赶而回想起往事。他起初根本不想报仇。他的梦想就是找到母亲和姐姐，夺回被抢走的房子，一家人像以前那样生活在一起。但好不容易找到姐姐，姐姐却在他面前被处死，於是龙决心报仇。他把父亲剑上的花纹刻在自己的心上。龙从当过小偷的养父身上铁蛋那学会行窃，得到有关士大夫的情报，终于第一次翻墙偷盗。因为在犯罪现场留下一枝红梅，龙开始被大家称为一枝梅。

经过一系列的事件，一枝梅对百姓而言不仅仅是义贼，而成为百姓心目中的英雄。此后一枝梅继续行窃，为百姓出气洗冤，大快人心。他时而像鲁邦，时而像马盖先，时而像佐罗……义禁府将领时厚非常想抓到一枝梅。而仁祖也虎视眈眈，想擒获被百姓之王的一枝梅。

围绕龙父亲之死不断发生令人质疑的死亡事件，而死者的身上都出现小小的伤痕。

由此暴露出惊人的秘密……有花纹的宝剑到底在哪……

一枝梅开始着手筹划最后一次超大型盗窃案！