On Graduation Day, Mystic Falls is overrun with ghosts intent on settling old scores and fulfilling their supernatural destinies.
Someone has been attacking patients at the hospital. A violent wind storm causes a power outage and ghosts suddenly appear -- some with good intentions and some bent on revenge.
Damon and Stefan try a brutal new approach to provoke Elena into turning her humanity back on, and Caroline is frustrated when her attempt to intervene backfires.
Klaus returns to his past in New Orleans and meets with his former protégé, Marcel, a charismatic vampire with control over the city's inhabitants.
When Caroline's plans for the perfect Senior Prom night are disrupted by Elena, she turns to an amused Klaus for a solution. Bonnie makes a terrifying discovery.
Shane leads an expedition to a desolate island off the coast of Nova Scotia, where he believes the secret of the cure lies hidden.