In 2019, Guo Weijie, a newcomer to the Binhai National Security Bureau, accidentally came across an old case. After investigation, he found that there was a lot of hidden truth behind the case. He has since embarked on the road to find the truth. But during the investigation, there is always someone who gets the clues before him. Who is this person? 19 years ago, Wu Yu from the Investigation Section caused casualties to a criminal suspect and was dismissed from public office. He has no reinforcements, no identity, only stubbornness and obsession, traveling all over the world, sticking to various targets, just to find the real criminal of that year. What will be the result?