MANSFIELD, Ohio -- A misty, full moon glowers over the stone turrets, a skirl of chainsaws and screams on the frosted air. A perfect night for fright.

And the setting, too, may be one of the best, the old Ohio State Reformatory, a veritable chateau of incarceration when it opened in 1896 in a field outside Mansfield, Ohio. The last inmate checked out in 1990, and, four years later, a local prison preservation group began stabilizing its leaky roofs and leprous walls. Halloween is the relic's time to shine.

In the haunted prison, maniacs with chainsaws pop out of dozens of cells and black holes. Cloaked monsters slither out of blackness to whisper in your ear, "We are the dwellers of the dark." And jumping out -- did we mention the jumping out? The prison's 970 cells make for a lot of jack-in-the-box heart-stoppers. And just as you try to catch your breath, ghoulish inmates on the other side of the cellblock rake metal against the bars and spike sparks in your face.

This year's production is "The Night 'They' Came Home," and your guide for the night will be Scaretaker, who dares you to meet him at the end of your tour. The path wanders through the wards and cellblocks of both the East and West wings of this Victorian behemoth, then exits through the old morgue -- can it get more haunted?

Fearless film buffs may recognize the soaring Central Guard Room from "Air Force One" and "The Shawshank Redemption," and other decrepit sets from "Tango and Cash" and "Harry and Walter Go to New York." But most of us are too busy hyperventilating and clutching each other's hands to do much sightseeing.

It's a good, wholesome fright, with about the right amount of eviscerated torsos and headless corpses -- plus, given the backdrop, plenty of bonus features: dummies of brutalized prisoners handcuffed to pipes, even one poor guy who met his maker in the state's electric chair, "Old Sparky."

Myron St. John and his wife, Lynne, have organized the fall mayhem for seven years, using a mix of animation, animatronics and, this year, 50 actors.

"These are highly motivated actors," deadpans Myron about the creatures who assail and assault us. Myron is also a "dweller of the dark," having worked as a producer, stunt man and "demon" actor for "Fallen Angels," a horror flick filmed in the reformatory and due in theaters this fall and on DVD by November. It stars Christopher Knight, Peter from The Brady Bunch.

The reformatory's chapel is now the macabre backdrop for "The Dead Matter," a horror-suspense film starring Andrew Divoff, the rogue with an eye patch, Mikhail Bakunin, on ABC's "Lost." Divoff's character, Vellich, held zombies enthralled in the chapel during a recent shoot.

But isn't all this zombie and ghost mania a bit like carrying coals to Newcastle? The reformatory is already renowned as one of the most haunted places in America. A crew from SciFi Channel's Ghost Hunters has spent nights at the prison recording unexplained encounters with spirits.

Psychics put the reformatory on their must-sense list, and, during the popular overnight Ghost Hunts, 100 paranormal investigators pay $50 each to prowl its decaying hallways. Some claim to spot Shadow Man, a full-spirit silhouette. Others report seeing an old lady in a green dress, and many pick up on the spirit of a little boy.

Dan Seckel is an architect on the Mansfield Reformatory Preservation Society (MRPS) board, the nonprofit group dedicated to saving this vast building. A non-believer in ghosts, he once forgot his flashlight on a tour.

"In the corner of the basement, I saw a young boy leaning into a corner like 'The Blair Witch Project.' When I asked a woman to shine her flashlight there, someone else said, 'Oh, did you see him, too?'

"This did start as a reformatory for young boys, so it would be common for them to be here," Mr. Seckel reasoned, still skeptical. "But if anyone asks me if it's haunted, I say darn straight it is," keen to the money-churning allure of spirits.

The society takes a 60 percent cut of the Halloween haul, funneling the money into restoration of the reformatory as a meeting center and tour venue. The society's mission is not only to save the structure for its sociological and architectural significance, but also to spur the old place into doing its part for the local economy just as it did for 94 years as a prison.

"The building was heavily compromised in the mid-60s, when the slate roof was taken off and it lost a lot of masonry detail," Mr. Seckel said. "But most of the interior can be restored to the 1890s design."

He proudly shows off the restored Warden's Quarters, open for tours at times other than Halloween. It has been returned to its 1890s heyday, full of Ohio products in every nook of the fireproof building: Zanesville's Encaustic tile on the floors, Cleveland sandstone and Sandusky blue limestone outside. The only flammable trims are walnut and oak.

"It's beautiful," he says in the foyer of the Warden's House. "You wouldn't want to lose something like this."

The state, however, had the reformatory set for the chopping block soon after its closing in 1990. Mansfield held a community meeting, gauging support for a lengthy campaign. By 1994, the new reformatory preservation society approached the state to take on the restoration project.

Members were able to save the original administration, warden's quarters and cell block areas. The power plant and workshops, where the prison's original young offenders learned new crafts, were demolished.

With funds from the Halloween haunted prison and Ghost Hunts, the preservation group has stopped the decay and restored sections of the building. The reformatory was designated an Ohio Bicentennial Site in 2003 and is also on the National Register of Historic Places.

These are tremendous honors for a seriously spooky place. Myron St. John set up a Ghost Cam so people waiting in line at the haunted house could track any paranormal action up the stairs.

His wife has smelled flowers and felt cold spots in the building, and he has had "someone brush up against me. But I consider that acceptable phenomenon, part of this old place."

Lee Tasseff, another society board member, has smelled a fresh cigar in the prison, which is totally non-smoking. He says that some ghost hunters realize they've captured flying orbs of light in the rooms once they develop their film.

"We tell newcomers to trust their intuition," said Frank Horvath, postal worker by day, ghostbuster by night. He directs the Ghost Walks for small groups.

"If they are drawn to a certain cell or room, take photos. If they feel they're being watched or followed, take pictures." High-speed film or camcorders with night vision can sometimes capture suspicious shapes and movements invisible to human night vision.

Of course, things will move too quickly during "The Night 'They' Came Home' for much photography. But Halloween visitors are invited back to the prison for Ghost Walks and Ghost Hunts throughout the year.

The only things never sanctioned within the reformatory's dank walls?

Seances and Ouija boards.

"There are already enough ghosts there," Mr. Tasseff said. "We don't want to open the portals to any more spirits."