Zhao Yu used to be a little ruffian who fought recklessly without any morals and bottom line, after being framed and sentenced to a lethal injection death penalty; Zhao Yu woke up reincarnated to a parallel timeline, where he's no longer a criminal, but a Key Case Investigation Team agent.

The change from a criminal to a police officer had thrown Zhao Yu off and had him wreak havoc for the first few days in the station. But with the help of a mysterious "Miracle system," Zhao Yu was able to embark on a new life where his goal is to solve the unsolvable cases and make amends for his past life mistakes.