Sylvester Stallone embodies "Rocky," a man who collects debts for a local Philadelphia crime boss, trains at Burgess Meredith's gym—referred to as "Mickey's"—and has feelings for Adrian, the quiet sister of his friend Paulie (played by Burt Young). Simultaneously, World Heavyweight Champion Apollo Creed (Carl Weathers) faces a setback when an injury prevents another fighter from competing. Fate then intervenes, and Creed chooses an unknown challenger—the “Italian Stallion.” The story that unfolds is a compelling account of perseverance as the champion believes victory will be effortless, while the challenger concentrates on going all sixteen rounds. While Stallone’s acting isn't conventional; he doesn’t so much play the role as become it—and this is what makes the film effective. Viewers are drawn into his world, his relationships, his training regimen, and his goals—much like the young Stallone likely felt while writing and producing the movie. The fight sequences are excellent, and the charm of the lead actor, along with trainer Meredith, contributes to the film’s enduring appeal. There are some inconsistencies in the storyline, but these are easily dismissed if you let the emotional core and strong performances capture your attention. It's a really good film.

Source on TMDB