'The Originals' season 4 spoilers, plot news: Neil Jackson, Christina Moses join cast

It was revealed at the San Diego Comic-Con by the show's star Joseph Morgan that "Sleepy Hollow's" The Headless Horseman actor, Neil Jackson, will be joining "The Originals" season 4. Jackson will play a vampire named Alistair.

He will have some dealings with Klaus (Morgan), of what nature is not known as yet. This was confirmed by Morgan during his interview at the San Diego Comic-Con press room.

Another cast addition is Christina Moses, the "Containment" series starrer, who will be portraying a doctor named Keelin on "The Originals" season 4. She will be the key to the survival of the Mikaelson clan. A bisexual werewolf, she will hold the answer to a likely cure to werewolf venom. She will be the Mikaelsons' prisoner.

Phoebe Tonkin, who plays the role of Hayley, shared some expectations at the Comic-Con regarding  her character's daughter. The actress confirmed that Hope, who was only two at the time of last season's finale, will be seven when the series opens with the new season.

in related news, Michael Narducci revealed that a five-year time-jump will take place from the events of last season's close up to the opening of "The Originals" season 4.

This is why, expectedly, Hope would already be a little girl by then and will have lines in the scenes, to exhibit the maturity that she has reached by then. Narducci also shared that Hope will have her own "hopes and dreams" and would be able to express how she misses her father as well as her appreciation of the losses that her family has sustained.

Hayley will also have a great task ahead of her. In order to find out how she can help the Mikaelsons, she would have to bring together seven werewolf packs. To do that, she would have to reach deep inside her and connect with her werewolf aspect.

In the meantime, Marcel (Charles Michael Davis) will be seeking counsel from a vampire, Sofya (Taylor Cole), who used to work for Lucien. He will also have an alliance in place with Josh (Steven Krueger).

Narducci pointed out at the Comic-Con, "I don't think Marcel is a villain. I don't think he's wrong. ... We'll have to see if there's anything in the world that might be able to mend these fences."

"The Originals" season 4 is expected to air early in 2017.