After some violent confrontations with his new classmates, Daniel LaRusso learns karate from Japanese handyman Mr. Miyagi, in order to defend himself.
A Vietnam vet breaks out of a mental institution to go after drug-dealing gangsters who are selling contaminated product that is killing people.
A delinquent teenager's only link to society is the attachment he feels towards an older brother-figure. When the older boy starts spending time with a new girlfriend, the teenager begins to feel even more alienated, and gets involved with drugs and the police.
A Texas Ranger and a ruthless narcotics kingpin - they were childhood friends, now they are adversaries...