Maggie and Meredith disagree with Derek about the best way to approach a patient's case, which leads to a bigger argument between the couple. Callie feels responsible when one of her veterans is pushed too far and results in a devastating diagnosis.
Isobel arrives in town and intimidates a shocked Alaric into arranging a meeting with Elena. Elena is horrified when she finally comes face to face with her birth mother.
Jenna is devastated by Isobel's unexpected arrival; Damon and Jeremy try to help Bonnie find a spell that will harness her ancestors' power.
After Abbie's sister escapes from a psychiatric hospital, Ichabod helps Abbie search for her; Ichabod and Abbie learn more about the evil they are facing, including its name.
When an unidentified, sickly boy is found in town, Ichabod and Abbie learn something disturbing is going on.