Paranormal Activity producer/found footage maven Jason Blum’s Blumhouse productions is targeting Stephen King in a big way at the moment. One of the two big projects bubbling away at the company in Mercy, which Peter Cornwell is busy developing to direct. He’s just hired Dylan McDermott to co-star.

McDermott, who last tackled a creepy tale with the first season of American Horror Story on TV, is joining the film to star alongside Frances O’Connor, Chandler Riggs and Joel Courtney.

Mercy, adapted from the short story Gramma that appeared in King’s Skeleton Key collection, finds two lads discovering that their grandmother – the titular Mercy – is a witch. Naturally, that will cause some problems for the family. O’Connor will play their mother.

Cornwell has Matt Greenberg- who last worked in the King realm with 1408 – on script duty and McG is also throwing his weight behind the project as a producer. There’s no word on when it’ll get shooting yet, but we’d expect cameras to be rolling within the next couple of months.

McDermott was last seen in The Perks Of Being A Wallflower. He’ll crop up in White House-under-siege action thriller Olympus Has Fallen. But we hope the producers of Mercy don’t think they’ve hired Dermot Mulroney. It’s so hard to tell them apart…