Hello Brother

A humanity-less Damon and Enzo are on a killing spree as per the vault monster's orders. Based on fresh leads, Stefan and Bonnie visit the slaughterhouse that Damon and Enzo now call home and try talking sense into them, but the duo are in no way even close to disobeying the vault monster. Alaric and his interns manage to delve deeper into the vault cave and discover ancient remains that have distinct Greek roots. Caroline has her hands full with finding clues and taking care of the kids along with the new nanny, Seline. On another side, Virginia St. John had escaped and gone straight for Seline. Caroline was right on time to save her kids, Seline and grill Virginia on spilling the beans about the vault monster but it was of no use, as Virginia bled to death. Bonnie was reminiscing about her and Enzo when she, along with Alaric, connected a similarity between a certain Greek story Enzo used to tell her and his current method of killing his victims. They all point towards Sirens or The Messengers of The Devil – a Greek myth according to which Fauns use mind control to lure their victims to their death. As the episode draws to a close, Damon and Enzo look on as the vault monster rises from the death pool with death gleaming in her eyes.

Plot summary from Wikipedia (CC BY-SA 4.0). Source