"Huan face" is a change of Pan's face. In the TV series "Happy Face", plastic surgeon Pan was accidentally held hostage on his way home. After waking up in an abandoned factory, he found his face changed. Later, he found that it was the face of a criminal named Song Kun. After that, Pan has been investigating the truth behind the scenes and finally found out the culprit.

Pan used to be a plastic surgeon in a hospital, but unfortunately he became a victim of a sudden change of face, which broke his dull and boring life and got him involved in a huge conspiracy. After changing his face, Pan lost almost everything, not only his job, but also his wife and son didn't know him. In order to reunite with his family as soon as possible, Pan began to investigate the truth of the matter. The man who gave Pan plastic surgery was a criminal caught by the police.

"Happy Face" is a suspense crime TV series, which tells that the hero Pan was originally an irrational plastic surgeon, and later began to investigate the truth because his face was unexpectedly changed. Pan didn't give up because of the change of his face. In order to return to his wife and son as soon as possible, he has been trying to investigate the truth of the matter. Finally, Pan finally caught the culprit, and the huge conspiracy hidden behind the face-changing gradually surfaced.

Song Kun is a wanted criminal by the police. In order to avoid the police and change faces with many people, he finally led a normal life as Li Yao, but Li Yao finally exposed his identity.