It turns out that people who are "sad to death" are infected with a virus, and this virus was infected after they were bitten by the insects inside when they went to see the hanging coffin. Buried in the hanging coffin is actually the sister of Pointed Hat, who is her grave keeper. Pointed hat comes from an isolated village. This village will have a plague caused by virus every 20 years or so, because this ancient village is popular with a "fitness method" that allows poisonous insects to suck their own blood, thus sucking away toxins from their bodies. It is this "fitness method" that makes people infected with the virus in poisonous insects, thus causing the plague. Pointed hat beloved sister is infected with this virus. In order to cure the plague, Pointed Hat left the village with her sister. He studied crazily and did research to treat her illness, but he couldn't accompany his wife, who couldn't bear loneliness and married another man. At this time, Pointed Hat's sister died of illness. According to the village custom, wearing a raincoat is for a relative of Dai Xiao, so he wears a raincoat all the year round.

Want to revenge his ex-wife, even the pointed hat of society went to the United States for research, and made a new virus based on the virus infected in the village. This virus will die of viral myocarditis a few months after people are infected, and they will be insane before they die. For example, when they see the red word "sad to death" and make incredible moves, Shang Xiaoman and others will also die. Pointed hat sent an email to Meng Siyao and others to lure them to see the hanging coffin, but his conscience was still alive. At the last minute, he advised them not to go. As a result, they went anyway and were infected with the virus. Why Meng Siyao? Because after Tiaotiao's ex-wife divorced him, Meng Siyao gave birth to someone else, and Tiaotiao killed Meng Siyao in retaliation for his ex-wife. Of course, the pointed hat saved Meng Siyao's life because he wanted Meng Siyao to die of his virus, not anything else. But in the end, he discovered through DNA that Meng Siyao was actually his own flesh and blood.

There are other main plots in this book. For example, Zhong actually has a second identity: the son of the president of a big company. The house rented by Meng Siyao is actually owned by construction expert Li Borui. He grasped several major crimes of that company and threatened to give him more money. The boss of that company, Zhong's father, sent someone to kill the Li Borui family. In order to find the evidence of the company and destroy it, Zhong was sent to rent Li Borui's building, but he found nothing in the search. Meng Siyao found that the secret was originally hidden in the interlayer of the room wall, but at the same time it was discovered by Zhong Fu. At this point, Zhong stood on the side of his beloved Meng Siyao and resolutely opposed his father's killing of Meng Siyao. In fact, he had secretly saved Meng Siyao's life before. Zhong Fu went into the wrong mezzanine when looking for evidence, and was designed by Li Borui: injecting a lot of gas to death. At this time, the pointed hat secretly called the police to rescue Meng Siyao.

Meng Siyao was taken to the hanging coffin by her mother when she was a child, because her mother couldn't forget the pointed hat, which is why Meng Siyao felt deja vu there. They also went to the village. In order to prevent them from being infected with the virus, people in that village first let poisonous insects bite them, then set them on fire and drench them with rain. Meng Siyao therefore produced virus antibodies, so he didn't die in the end. However, Zhong had no antibodies and died. Of course, the ending is very strange: Zhong died, and Meng Siyao also received his short message, saying: Drink spring water under the Nirvana cliff, and guess what I made a wish? I got what I wanted, and I'm satisfied.