Detective Training Manual

Be careful: never dig into mysteries that have never been solved. Because you will never know what the people of that time paid in order to cover them up. Beneath the surface of false calm, most truths are cruel... Fine, let me put it more plainly. If one day, on your way home from work, you see a book lying on the ground, rein in your curiosity and absolutely do not touch it.

...Unfortunately, the original Zhou Yan did not understand that. So he picked up that book. It had a very awkward name: "The Detective Mastery Manual." As for the author... he was called Feigua.