S6, E18: With their humanity turned off, Stefan and Caroline begin wreaking havoc at Whitmore, leaving Damon to come up with a risky plan involving Lily (recurring guest star Annie Wersching). After rushing to help Jo (recurring guest star Jodi Lyn O’Keefe) treat victims of Stefan and Caroline’s latest killing spree, Elena discovers Jo is pregnant, prompting her to reevaluate her own life as a vampire. Meanwhile, when Sarah (recurring guest star Tristan Mays) boldly turns the tables on an unsuspecting Enzo, he is forced to open up about his tragic past. Lastly, at Scull Bar, a twisted round of karaoke leaves Tyler and Matt in a dangerous situation.