What are the loopholes in the movie Kidnapper?

At the beginning of the movie, which is full of loopholes, Yang Nian (played by Huang Lixing) calls a policewoman to say that her daughter has been kidnapped. In her own hands, she was knocked down by a big truck, and then her position was exposed. The car accident made her lose her memory. The policewoman rushed to the scene and asked her daughter where she was out of control. The story begins, and the two main lines that are clear throughout are presented like this: the policewoman lost her child and the kidnapper looked for memories. The whole story is ups and downs, and the case is confusing, no.

In the plot, the daughter of police officer Vivi Lin (Bai Baihe) suddenly disappeared, while the only suspect, Yang Nian (Huang Lixing), suffered a car accident on the night of the murder and lost her memory. On the way to escape in pursuit of clues and memories, Yang Nian was assassinated constantly, and Vivi Lin, who was bent on finding his daughter, followed him step by step at all costs. Lu Ran (Ming Dow), the leader of the major crimes unit, helped Vivi Lin at a critical moment. The truth is stripped away layer by layer. ...

In the process of searching for her daughter, Vivi Lin found that there might be a mole among the police brothers who fought alongside her. She couldn't confirm who this person was, but Yang Nian pointed the finger at Vivi Lin's best friend Liu Ran in the process of "cooperation" with her. Vivi Lin suspects anyone, but refuses to doubt Liu Ran. But at the end of the story, he finds that Liu Ran is the chief culprit in this child kidnapping case, and the real reason is that Liu Ran's sister is ill. In order to find a matching kidney source in time, he does not hesitate to kidnap the child. Here, Lu Ran was kidnapped by his family.

Vivi Lin was also kidnapped. In order to find her daughter, she almost lost her mind. She lost her gun, disobeyed the leader's orders, and was kidnapped by friendship. When she pointed the finger at Liu Ran, she didn't want to doubt or even continue to investigate.

The ultimate reversal is not only that Lu Ran is Vivi Lin's best friend, because his sister's incident has become the culprit of the kidnapper, but that the kidnapper Yang Nian is also a policeman and exists as a top secret figure in order to uncover the mystery of the child kidnapping case.