North American Detective: I am Proficient in All Kinds of Gun Quick Draws

【Gunfight + Mystery-solving + Decisive Killing】 I had already been backstabbing the underworld, and now you're telling me I was planted as an undercover cop??? Dean looked at the boss with eyes that would not close in death, scratched his head, and could only take the opportunity to transform into Los Angeles' five-star good citizen—Detective Dean! Ps: There's nothing supernatural, but there is a dark world out of our ordinary reach, filled with assassins, thieves, and all kinds of bizarre cases...