David Chisum as Jim Brown, Franka Potente as Kassie, Jessica Lange as Sister Jude on “American Horror Story: Asylum.” (FX)

FX has ordered a third round of “American Horror Story.”

The drama series turned miniseries will launch its third iteration in the fall of 2013; 13 episodes are ordered this time.

On the downside, FX and creator Ryan Murphy were keeping mum as to what the third iteration would be about. The first season was set in a haunted house, while season 2 is set in an asylum for the “criminally insane.”

FX did confirm, however, that Jessica Lange is returning for the next season, though it would not say in what role.

Lange, the lead thespian of “American Horror Story” Rep Theatre, this year is playing sadistic Sister Jude, the head nun in charge of administration and discipline at the asylum who is very much front and center. FX vowed in Thursday’s announcement that this time Lange will be submitted for all trophy consideration as a lead actress in a movie or miniseries — none of this supporting-actress nonsense, like last year. (Lange won both the Golden Globe Award and a Primetime Emmy for playing weirdsmobile Constance Langdon in the first season of “AHS.”)

News of the pick-up comes the day after the most recent episode of “American Horror Story: Asylum” topped all broadcast networks at 10 p.m. among 18-34 year olds, who are the holy grail of TV ad sales.

FX likes to boast that the median age of this season’s “AHS” is 33 years old, which is impressive for a drama series since they tend to skew older than comedies. NBC’s freshman drama “Revolution,” for instance, has a median age of 45.6 years.

So far this season, “AHS: Asylum” is averaging more than 5 million viewers of all ages. The franchise ends its second run on Jan 23.

“American Horror Story” was originally purchases by FX from from Murphy and Fox as a drama series set in a haunted house.

But after the first season finale aired, Murphy announced the second season, and every season thereafter, would be a re-boot, with no relation to the first season, though some new characters would be played by some returning actors.

The second season was set in an asylum, as its name suggests. (The first “season” now sports the name “American Horror Story: Murder House.”)

“[T]he notion of doing an anthological series of miniseries with a repertory cast — has proven groundbreaking, wildly successful and will prove to be trendsetting,” FX chief John Landgraf said in Thursday’s news.