Aidan was a Revolutionary War soldier who sacrificed himself to vampires to spare his men. Now, some 260 years later, he is still struggling to escape the orbit of his powerful mentor, Bishop. Josh was a promising medical student forced to abandon his family and future after a werewolf attack left him cursed. And Sally, happily engaged before her tragic death, must now figure out how to move on as a ghost.

Aidan tries to steer a leaderless Boston while resisting his deadlier vampire instincts as he finds himself tempted and tormented by a figure from his past. Sally must face the consequences of missing her door while figuring out how to navigate life on earth as a ghost. Josh searches for a cure for his condition while struggling to maintain his relationship with Nora and, like the rest of his roommates, trying to build a future for himself beyond simply being a monster.

Returning from limbo leaves Sally with more baggage than she bargained for, as well as new abilities that prove to be both a blessing and a curse. Josh deals with the consequences of attempting to lift his werewolf curse and his life is further complicated when an ominous visitor comes to Boston looking for him and Nora. Aidan resurfaces from being grounded and finds the vampire community vastly changed; he must find a new approach to feeding that will change his life forever.

Sally struggles to contain her newly acquired powers and break free of Donna's hold on her, while also seeking out the truth behind a murder mystery that haunts her when her powers are used.