I am hurt. A plague o' both your houses! I am sped. Is he gone and hath nothing?
Mercutio and Benvolio are at a fair minding their own business until Tybalt and his friends showed up looking for Romeo, to fight him. When Romeo shows up he doesn't want to fight but Tybalt won't let him leave . Then Mercutio steps in and fights for him.
Then Romeo tries to stop the fight but distracts Mercutio and that's when Tybalt takes that opportunity to stab Mercutio with a knife. Then Mercutio dies shortly after.
My lord, I would that Thursday were to-morrow
Romeo feels as though Mercutio's death is his fault. And to avenge him he goes after Tybalt saying that either he or Tybalt or both of them will die. And then Romeo killed Tybalt.
Here Juliet awaits her Romeo, unknowing that he killed her cousin Tybalt and was banished from the city of Verona for doing so.
Here is Sir. Capulet and Paris discussing an arrangement for Juliet to be married by Thursday.
Romeo found a way to sneak into Juliet's room and spend the night "playing twister" and now has to leave before sun rise or else he will be caught.