Iron nematode is a kind of parasite. Parasitism mostly occurs in arthropods, which will take nutrients from the host, grow to be as heavy as the host, and later take over the host's body functions and even control the host's brain. ? 　

In the movie, iron nematodes parasitize and develop in the human body, and when they mature, they will return to the water to breed. Therefore, the infected people are like walking dead, step by step towards the water source, and finally die tragically.

The hero Zahe is a clerk of a pharmaceutical company and a doctor of medicine. He has three experiences of buying medicine for his wife and children. Zahe's book of buying medicine has bought many different kinds of people, and the biggest struggle is that he can't overcome this problem in his professional field, but he relies on the world instead. But compared with the families of other patients, at least he can actively find ways to get rid of the predicament, while others can only give in easily.

At the end of the film, did you deliberately leave a suspense? When his wife and children recovered, Zahe played in the playground with his wife and children, saying that he would take them to travel abroad, but Zahe also said that he would travel to places with many pharmacies, and then a person jumped into the pool, which seemed to mean that the "iron worm invasion" was not over. First of all, it was not clear whether there was a sequel to explain it in detail. Secondly, I preferred to think that this was not another time for human beings to make iron worms mutate for profit.

It may be a revenge of the parasite itself for human beings. Huge human beings tend to despise insects. In fact, both human beings and insects are animals. Using parasites parasitic in insects to turn back on human beings has aroused people's panic, and it can better warn human beings that they can not always pretend to despise insects as huge thinking animals.

We often look at the smallness of insects from the perspective of human beings, and it is possible to trample a worm to death with one step. This is actually not the law of the jungle in Darwin's theory, because human beings do not take insects as their main food, but they take whatever they want from insect life by various physical and chemical means, and insects will do nothing in the long-term evolution process? Humans will deform and insects will mutate. How we look at insects is actually how we look at ourselves.