West Side Story takes place in Manhattan in 1957. A war breaks out between an American and a Puerto Rican Gangs, the Jets and the Sharks. These gangs are headed by Riff and Bernardo respectively. After they are subdued by Lieutenant Schrank and Officer Krupke, the Jets dare the members of the Sharks to another fight with them during an upcoming dance.
Riff invites his best friend and former member of the Jets, Tony, to come to the dance so that he can use his skills when their group fight the sharks. Tony refuses, telling him that he something extraordinary may happen during that time.
Bernado’s younger sister, Maria and her best friend Anita attend the school dance. There she meets Tony and the two immediately develop feelings for each other. Bernardo finds out about this and he warns Tony to leave his sister alone. To protect Tony, Riff suggests to Bernard that their gangs should hold a council to which Bernardo readily agrees.
When they get home, Bernard leaves again to attend the council. Tony arrives and spends time with Maria. Before he can leave. Maria tells Tony to meet her at the bridal shop after closing time.
Meanwhile, the gangs commence their council at Doc’s drugstore. Tony also arrives and suggests that the two gangs settle their differences with a one-on-one fist fight. Both groups agree. The Sharks choose Bernardo as their representative while the Jets opt for Ice. Afterwards, Tony confesses to Doc that he’s in love with Maria. Doc warns him about the dangers of delving into such situation.
The next day, Maria learns from Anita about the upcoming fight between the gangs. At the moment, Tony arrives and shocks Anita. When she learns of their feelings for each other, Anita advises Maria about what her brother will do if she and Tony continue their relationship. After Anita has left, Maria asks Tony to do everything he can to stop the fight.
Before the end of the day, members of the Sharks and the Jets prepare for the fist fight but Tony arrives and tries to dissuade them from pursuing the battle. Because of this, Bernardo starts insulting him. Riff gets enraged and hits Bernardo. Both men then engage in fighting while Tony desperately tries to get in between them. When Bernardo kills Riff, Tony also stabs him with his friend’s knife. Upon seeing what has happened, the gangs escape and Tony is left with a bloodied knife on his hand. A girl member of the Jets, Anybodys, pulls up Tony and escapes the crime scene with him.
While waiting for Tony, Maria learns about what happened to her brother. Tony arrives and begs Maria to forgive before he turns himself in to the police. Out of her love for him, Maria tells to Tony to stay with her.
As the Jets are discussing on what they should tell the police, Anybodys comes and informs them that someone from the Sharks is hunting Tony. Ice, the man who took over Riff’s position, sends out the other members of the gangs to warn Tony.
Before he leaves, Tony asks Maria to meet him at Doc’s drugstore and come away with him. Anita comes in and sees him as he makes his way in the alleyway.
Meanwhile, the police arrive to question Maria. Maria then asks Anita to meet Tony and tell him that she will be a little late. Anita goes to the drugstore but the Jets disbelieve that she comes with good intention. Before they can do anything bad to her, Doc comes to the rescue. Enraged by the harassment done to her, Anita tells them that Maria is killed because of her love for Tony.
Tony arrives and hears from Doc the wrong message delivered by Anita. Because of shock, Tony rushes out to find Maria. He spots her in one of the streets. Before he can reach her, Tony gets shot by Chino. The Sharks and the Jets together with Doc arrive at the scene. Before they can start another rumble, Maria snatches the gun from Tony’s shooter and threatens to kill as much as she can before she takes a bullet for herself. She blames the gangs for causing Riff, Bernardo, and Tony’s death. However, she can’t bear the thought of killing so she lets the gun drop from her hands. The movie ends with the members of both gangs carrying Tony’s body and Chino getting arrested for his crime.