Joseph Morgan, Daniel Gillies

The Vampire Diaries is flashing back to the 12th century and star Joseph Morgan says that viewers should pay close attention.

On Thursday's episode, Klaus delves deeper into the new mysterious bad guy in town, Connor (Todd Williams), and in the process reveals a past (and eerily similar) encounter he had with a very powerful group of vampire hunters.

"We learn a huge secret that fits into the mythology of Mystic Falls and of the Originals' history," Morgan says in the video below. "It's really a big reveal and will play a dominant part in how the season evolves." Executive producer Julie Plec also tells us, "The question of what is different about [Connor], why is he able to deeply, darkly hunt and kill vampires, what drives him, what his history is and what other people know about his history start to unfold ... in that flashback."

Keep watching for more from Morgan on how "The Five" stacks up among his favorite episodes and which Klaroline scene previously topped his list.

Watch The Vampire Diaries Thursdays at 8/7c on The CW.