Finally, there's some major progress with the still-untitled spin-off of AMC's "The Walking Dead."

The show has cast two of its main stars: Frank Dillane ("Harry Potter and the Half-Blood Prince") and Alycia Debnam Carey ("Into the Storm"), according to Deadline.

Deadline didn't specify which roles Carey and Dillane will play, but did give brief descriptions of the characters. The two will be brother and sister on the spin-off, with Dillane playing a troubled son who used to have a drug problem, and Carey as an ambitious daughter. The mother, a former guidance counselor, is still being cast.

AMC previously released character descriptions of the cast, and it's possible Dillane will play Nick Tompkins and Carey will be his sister, Ashley Tompkins. The new series "takes place during the same zombie apocalypse depicted in 'The Walking Dead' but in a different location," according to Deadline. 

Shooting is expected to begin in Pennsylvania soon, but has not been given a premiere date yet. The show will center on the female guidance counselor and a male divorced teacher, Deadline reported.

The main character descriptions are below:

Sean Cabrera: a Latino male in his early 40s who is "a good man trying to do right by everyone in his life." Sean sounds like the show's protagonist and could be similar to Rick Grimes.
Cody Cabrera: Sean's teenage son who is known as the "angriest kid in town." Cody is really smart but rebellious.

Nancy Tompkins: a 30-something single mom of two. She is described as the girl-next-door type but with an edge.

Nick Tompkins: Nancy's "screwed up teenage son" who is too old to still be living with his mother but is too scared to leave

Ashley Tompkins: Nancy's teenage daughter who is the complete opposite of her older brother. Described as "mostly level-headed" and has "ambitions in direct proportion to her older brother's failures. She loves her mom but it's time to get out of dodge."

Andrea Chapman: a 40-something "somewhat wilted flower child" who escaped to the outskirts of the city to recover from a bad marriage.