When The Hollow sends a terrifying message to Vincent (Yusuf Gatewood), he must team with Haley (Phoebe Tonkin) and Freya (Riley Voelkel) to embark on a desperate mission to stop the Hollow once and for all - even if it requires a heartbreaking sacrifice. Refusing to allow anyone in his family to pay the high price of defeating their enemy, Klaus (Joseph Morgan) makes a surprising alliance and enacts a plan that threatens to change the Mikaelson family forever.