Main character Liu Ziguang washes ashore on a beach with no memory of his last eight years (though we the viewers know much of it, with a few key pieces of information hidden from us as well). He discovers that he's really good at fighting, almost superpowered in terms of athletic abilities, and he can shoot guns. What happened in those eight years?
Back in his hometown (Jiangbei), he saves a boy from kidnappers but draws the suspicion of a feisty female police officer (Hu Rong). He also reunites with some childhood friends and does a lot of local heroic deeds.
The main driver of the plot is the mystery of those eight years, combined with the drug trafficking going on in Jiangbei, which it turns out he has some connection to. Meanwhile, he and Officer Hu gradually fall for each other, though not without complications.
There's actually a lot of comedy in the series, though not so much in the last eight or nine episodes. Other parts are heartbreaking -- credit really goes to actress Ma Sichun, who shows incredible range, going from tough and determined, to lovey dovey to utterly devastated.