Rocky III is a 1982 American film that is the third installment in the Rocky film series. It is written and directed by and stars Sylvester Stallone as the title character, with Carl Weathers as former boxing rival Apollo Creed, Burgess Meredith as Rocky’s trainer Mickey, and Talia Shire as Rocky’s wife, Adrian.

After beating Apollo Creed and becoming World Heavyweight Champion, Rocky Balboa is enjoying his boxing and wealthy lifestyle. After 10 successful title defenses and a charity fight draw with World Wrestling Champion, Thunderlips, Rocky believes he has nothing more to prove and is ready to retire. Boxing’s no. 1 contender is James ‘Clubber’ Lang, played by Mr. T. Lang is a younger and more aggressive boxer than Rocky. He is brash, arrogant, outspoken, and immensely strong. Lang demands a match with Rocky for the title. Rocky has too much pride to reject Lang, and trains half-heartedly for the bout.

Before the match, Rocky and Clubber get into an argument backstage and Micky suffers a heart attack. Rocky enters the fight very worried about Micky who is being treated by a doctor. Lang brutally beats Rocky, and after the fight, Rocky attends to Mickey, who dies in the dressing room.

An angry Rocky becomes depressed and detached. Former Champion Apollo Creed is the only man able to persuade Rocky to attempt a rematch, and after Lang accepts the challenge, Creed trains Rocky. Rocky must now try to forget about his last brutal bout with Clubber, and try to regain the title and the confidence of everyone, and also try to get back the ‘eye of the tiger’.

Summary via Wikipedia.