Johnny Lawrence devoted his life to studying martial arts, but after losing in the finals of the karate tournament to Daniel LaRusso, he decides to retire from the sport. After 30 years, he has not been able to achieve at least some success in life, interrupted by odd jobs. And his abuser, who once won against Johnny, became a famous businessman selling cars.
One day, a former karate fighter witnesses the beating of his neighbor, a shy young man Miguel, by a group of angry teenagers. The man chases away the hooligans, but for beating minors ends up in the police station.
Upon learning of what happened, Miguel's stepfather pays a deposit for his stepson's defender and hands him a considerable amount of money. The guy asks the former athlete to teach him the basics of karate, but Joni refuses. He recollects and, having gone too far with alcohol, gets into a car accident, the culprit of which is the daughter of his old friend LaRusso. Once again meeting the man who broke his life, Lawrence agrees to help the insecure Miguel and become his sensei, he announces the opening of a karate school called "Cobra Kai". Now he intends to prove to his longtime opponent that he is also capable of achieving success and helping novice karatekas achieve excellence in martial arts.