Romeo and Juliet fall in love, only to realize that they are on opposite sides of an ongoing war between their families. Act I ends with the lovers pursuing their affair in the famous balcony scene. Swoon!
Romeo is banished from Verona for—oops!—killing Juliet's cousin Tybalt, so the Friar has Juliet fake her death so she can join Romeo in Mantua. Great plan, right? Well, it might have been—except that Romeo doesn't get the message that she's actually still alive.
Romeo kills himself next to Juliet's comatose body; when she awakes, she kills herself in response to finding his corpse. The one upside? The families finally end their cycle of hate.