Before Romeo departs for Mantua, Juliet shares with him her premonition. What is it?

Juliet's premonition, which she says is the product of an "ill-divining soul," is of Romeo's dead body, lying in a tomb.

Methinks I see thee, now thou art below,
As one dead in the bottom of a tomb.
Either my eyesight fails, or thou look'st pale.

Romeo downplays the vision, but the audience knows, having been told as much by the Chorus, that this vision is fated to come true for the "star-cross'd lovers." Romeo's banishment from Mantua proves to be fatal to the lovers, as a quarantine prevents Friar Laurence from telling Romeo that Juliet is only pretending to be dead. Balthasar, Romeo's servant, knows nothing of the Friar's plan, and he reports to Romeo that Juliet is actually dead. This causes Romeo to go to the Capulet family crypt and commit suicide next to Juliet's seemingly lifeless body. When Juliet wakes up, she sees Romeo's corpse lying in a tomb, just as she envisioned. Her premonition comes eerily and tragically true.