To readers who think it’s fun to be frightened, Mary Downing Hahn is a haunted household name. Kirkus declares her “a master of the supernatural tale.” Longtime publisher Clarion calls her “the Queen of Tween Screams.”

“It’s a funny thing,” says Hahn, who’s best known for exquisitely chilling middle-grade ghost stories, “because when I was a kid, I was probably the biggest scaredy-cat” in her hometown of College Park, Maryland.

At age three, she mortified her parents on holiday in nearby Ocean City by screaming her way off the merry-go-round. (“I can still remember, it was a black horse that went up and down, and he had really big teeth.”) On her seventh birthday, she hid under a movie theater seat, pressed to the sticky floor, to escape Disney’s Snow White and the Seven Dwarfs. (“I was absolutely terrified.”)

“But what I was really scared of,” she says, “were the things that came in the dark when I was alone, in my room, trying to go to sleep. I was afraid of death and dying—that was an obsession of mine as a child, I wouldn’t go near a graveyard—and I never would have read the kind of books that I write.”

Not the ghost stories, anyway: Wait Till Helen Comes(1986), The Old Willis Place(2004), and Deep and Dark and Dangerous(2007), et al. (Hahn has also published works of historical fiction, mystery, contemporary middle grade/YA fiction, and fantasy.) And not her forthcoming novel, The Girl in the Locked Room(Sept. 4), a claustrophobic thriller that sprang from a spooky image in its author’s mind.

“An image of this child locked in a room,” Hahn says. “She doesn’t know why she’s there, or even who she is, or how much time has passed. I just felt this voice telling me the first couple of chapters in the book, of this little girl in the past. Then, I figured out how to weave her story into the present—I was going to have two points of view.”

A second character, a modern girl who discovers the ghostly presence when her family moves into a dilapidated old mansion, resolves to help unlock the mystery (and the door).

“A lot of times when I’m writing,” says Hahn, “I know the narrative’s going the way I want it to when I feel like the characters have so much come to life, they’re almost dictating what happens. It’s a strange feeling, like you’ve given up control over writing—it’s taken control of you—and these ideas come into my head...and sometimes, they scare me. What kind of mind do I have that these things are in there?! And I’m letting them out, to frighten other people.

“And yet,” she says, “they seem to love being frightened.”

Though she’s come a long way from her Snow White days, Hahn still prefers her recreation devoid of thrills and chills. You won’t find her and a group of friends at “Escape the Room” anytime soon, for example.

“Really!” Hahn remarks, on learning of the existence of places where adults pay money to get locked in a room, play games, and solve puzzles to gain their freedom. “Oh, I’m not going there. I’m not going into a locked room to try to figure out how to get out. That’s terrifying.

“That’s why it’s better to write a book,” she says, “because, thank goodness, I can always escape the book—by writing something else—if it’s really bothering me.”

Megan Labrise is a staff writer and co-host of the Fully Booked podcast.