West Side Story is a 1957 Broadway musical inspired by William Shakespeare's play Romeo and Juliet. 

In the summer of 1957 in the West Side's Lincoln Square neighborhood in Manhattan, there is tension between a white gang, the Jets, led by Riff, and a Puerto Rican gang, the Sharks, led by Bernardo. After a brawl erupts, Lieutenant Schrank and Officer Krupke arrive and break it up, ordering both gangs to cease all fighting, or face the consequences. Despite their warning, the Jets decide to challenge the Sharks to a rumble for neighborhood control, at an upcoming dance.
Riff decides that his best friend Tony, the co-founder of the Jets who left the gang, and works at Doc's drug store, should fight. Riff invites Tony to the dance, but Tony is uninterested. He tells Riff that he senses something important will happen, which Riff suggests could have a correlation with the dance.
Bernardo's younger sister, Maria, tells her best friend and Bernardo's girlfriend, Anita, how excited she is about the dance. At the dance, the gangs and girls refuse to intermingle. Tony arrives and he and Maria fall in love. However, Bernardo angrily demands that Tony stay away from her. Riff proposes a meeting with Bernardo at Doc's drug store.
Maria is sent home; Anita argues that Bernardo is overprotective of Maria and they compare the advantages of Puerto Rico and the United States.
Tony discreetly visits Maria on her fire escape, where they reaffirm their love. Krupke, who suspects the Jets are planning something, visits them and warns them not to cause trouble. Doc, the owner of the drug store also discourages fighting, but no one listens. When the Sharks arrive, both groups agree to have the showdown the following evening under the highway, with a one-on-one fist fight, under the suggestion of Tony. When Schrank arrives, the gangs feign friendship. Schrank does not buy it, and orders the Sharks out and unsuccessfully tries to get the Jets to divulge the location of the fight. After everyone else leaves, Tony tells a concerned Doc about his love.
The next day at the bridal shop, Anita accidentally tells Maria about the rumble. Tony arrives to see Maria, which shocks Anita. They profess their love and Anita warns them about the consequences if Bernardo learns of their relationship. Maria has Tony promise to prevent the rumble. Tony and Maria fantasize about their wedding ceremony.
The Jets and Sharks approach the area under the highway. Tony arrives to stop the fight, but Bernardo antagonizes him. Unwilling to watch Tony be humiliated, Riff initiates a knife fight. 

Maria waits for Tony on the rooftop of her apartment building when Chino arrives and tells her what happened. Tony arrives and explains what transpired and asks for her forgiveness before he turns himself in to the police. Maria confirms her love for him and asks Tony to stay with her.
The Jets have reassembled outside a garage, with their new leader, Ice having them focus on their reaction to the police rather than their rival gang. Anybodys arrives and warns them that Chino, armed with a stolen handgun, is searching out Tony for revenge, so Ice sends the Jets to warn Tony of the danger.