Plot summary
Cade frees Stefan from captivity and sends him on a mission. He then tells Damon that his work isn't cutting it and that by sundown he must either kill one hundred people or Caroline. Bonnie encourages Enzo to complete his bucket list before taking the cure; once complete, they travel to a house she bought in New York where she is secretly keeping Elena. Caroline and Damon scheme to give the cure to Cade so that they can kill him and Bonnie reluctantly agrees to draw Elena's blood and give them the dosage instead of Enzo.
Cade later reveals that his mission for Stefan was also to kill a hundred people or Elena. Stefan chose the latter and so Damon races to New York to stop him. Stefan compels Bonnie's realtor to sign the house over to herself and then invite him in so that he can get to Elena. Bonnie draws the blood from Elena and then gives it to Stefan after Stefan arrives at the house and kills Enzo.
Credits
Adapted from Wikipedia contributors, The Vampire Diaries season 8. HTML formatting and reference markers removed.