It chronicles the life of a Temporal Agent sent on an intricate series of time-travel journeys designed to ensure the continuation of his law enforcement career. Now, on his final assignment, the Agent must recruit his younger self while pursuing the one criminal that has eluded him throughout time.

In the final season of A Discovery of Witches, Matthew and Diana return from their trip to 1590 to find tragedy has occurred at Sept-Tours. They must locate the missing pages from the Book of Life and the Book itself before it's too late. But their enemies are gearing up against them, and a monster from Matthew's past has been lying in wait to return for revenge.