A musical Romeo and Juliet story.
The Sharks and the Jets are two feuding street gangs in 1950's New York, the Jets being White and the Sharks being Puerto Rican. At a dance at a gym, Jet Tony falls in love with a Shark's sister, Maria. They know they can't be together because of the gang's war, but that doesn't stop them.
Meanwhile, The two gangs prepare for a rumble, and Tony tries to stop it out of love for Maria. In the process, his best friend and Jet leader Riff is killed by Maria's brother, Bernardo. In anger, Tony kills Bernardo. HE then realises his mistake (killing his love's brother) and begs for forgiveness, which, of course, Maria gives him. They decide they have to leave the city, and the pointless hate, behind them. They plan to meet at Doc's Candy Store and take a bus to the country.
Maria asks Anita, Bernardo's fiancé, to tell Tony she will be a little late meet him at Doc's Candy Store, but when Anita is mauled by the Jets, she angrily tells them that Maria is dead, murdered by Chino, which is, of course, a lie. Doc overhears this and reluctantly tells Tony. Tony is devastated and furious, and hunts Chino down so he can be killed too.
Tony runs into Maria at the playground and is overjoyed. As soon as they embrace, Chino runs in with a gun and shoots Tony. Tony tries to stay alive but is overcome by the bullet and dies. Maria bursts into tears, devastated, and when the police come, both Jets and Sharks help carry Tony away. Baby John places Maria's head scarf on her head and Maria is the last to walk out.