It's a raw and painfully cold winter's night, and if there's one place you'd rather not be at such an hour, it's a haunted medieval building. Provan Hall, in Auchinlea Park, Easterhouse, dates from the 15th century and is one of the oldest properties in Glasgow, reputed to have not one, not two, but three ghosts.
Normally, I'd be all for letting sleeping dogs lie but tonight, together with a group of strangers, equipped with torches and layers of warm clothing, I'm here because of an ingenious fundraising venture dreamt up by the South Lanarkshire branch of the National Autistic Society (NAS).
The six-hour-long investigation is being undertaken by researchers from Lanarkshire Paranormal, who have arrived with cameras, recording equipment, TV monitors and EVP recorders. The EVP stands for electronic voice phenomena, which, as one ghost-hunting equipment website explains, "is sound potentially caused by ghosts in order to communicate with us from the beyond".
The group is split into two, and tackles the haunted rooms at different times. The procedure is the same. The room is utterly dark. People sit at tables, the cold eating into their bones. "Hello, is there anyone there?" one of the investigators calls out. "We'd just like to talk to you. We don't mean you any harm. We know you're here. Come on, come and see us."
Silence. A dark, chilled silence. A table creaks, or maybe it's someone's knee joint. The merest sound is magnified, and can make people's hearts skip a beat. There's a perceptible thrill of excitement: while everyone else is at home, in bed, here we are, trying to contact the restless spirits of the dead.
The investigator calls out several times in a friendly way. No spirits respond. But the other group is bravely carrying out a seance in one of the old rooms. They later report that it was as if someone was thumping against the wall, causing bits of plaster to fall off.
Janice Murdoch-Richards, Lanarkshire Paranormal's manager and co-founder, says: "Usually the first couple of hours are not that busy, but once the energy lifts up …" She pauses. "We've had tables lifted up, chairs moving. The last time we were here, the public were sitting around in one of the rooms and we were calling out, and we saw a tablecloth coming off the table and dropping to the floor. Everybody just screamed."
As Murdoch-Richards says these words I suddenly regret sending away the taxi that brought me here.
The group's equipment also includes dictaphones. "Sometimes," says Murdoch-Richards, "we hear voices, but it's not very often. But then we come home and play the dictaphone back, and find we've caught a lot of voices on it.
"The first time we were here, we were told to get out. We went upstairs to set things up and heard it quite clearly." Her voice drops an octave. "'Get out!'" She laughs. "I was like, OK …"
Murdoch-Richards speaks of the "gruesome" history of Provan Hall: how, hundreds of years ago, a returning soldier found his wife had given birth to a boy with another man. The soldier killed both his wife and the child.
"She's been seen here, and the little boy, walking along the courtyard," she says. On a recent investigation, footsteps were heard, and a night-vision camera caught what may have been the face of the soldier.
Tonight, it seems someone - or something - has been unplugging all the team's cameras.
As the clock inches past midnight into the early hours of Sunday, we visit all the rooms, and wait, and wait, for something or someone to respond. We hang around stairwells, sit around tables, listening for the slightest creak or movement. Every so often, we repair to Provan Hall's main public room, where Steve Allan, the caretaker, ladles out soup, tea, coffee and rolls.
Then it's back into one of the reputedly haunted medieval rooms. We're congregated in front of a doorway when, suddenly, something happens.
An investigator has been trying to contact a young child when Linda Morrow, from the South Lanarkshire branch of the NAS, is overcome, and appears upset. Her sister seems to have been affected by something too. Understandably, it causes a commotion. When I talk to her a few moments later, she seems pale.
"It was all really intense emotion," she says. "It was all of a sudden, just like that," and she snaps her fingers. "We could feel something really cold between us.
"I just kept feeling there was a girl, and she was looking for her sister. She just had to get to her, and she didn't know where she was. One minute I was OK, the next minute it was as if I could feel some anxiety, someone's real distress.
"My sister said she felt as if there was someone pulling her towards the room. She felt as if someone was gripping her hand, there was a pulling sensation as if she was being pulled towards that closed door."
The ghost-hunt continues. No spirits appear but there are little moments when, in the dark and that silence, in these centuries-old rooms, you could sense something watching.
One incident, however, is my fault. A crowd of us are sitting in the dairy, gazing at an electromagnetic field meter on the floor; its flickering lights would register a ghost's presence or movement. The silence is arctic.
I'm leaning against a wall and as I shift my weight I lean more heavily against it than I intend to. The noise in that silence is like a pistol shot. Everyone jumps. At least the darkness spares my blushes.
Eventually, the six-hour ghost hunt draws to a close. One woman says she experienced a stabbing sensation in the back. A couple of others have taken unwell. Some report that their wrists have been squeezed in the darkness. One hardened sceptic, standing in the dairy, says he felt as if someone was pulling on his arm and wouldn't let go. He could see his arm physically being moved against his will.
"We thought it was going to be a slow night but it passed very quickly," Morrow says later. "There was a lot of activity, and that was corroborated by the second group when we all got together at the end."
It was a while, she tells me, before she was able to put her commotion out of mind.
"For days afterwards," she says, "I was very tired and had weird kinds of dreams. Nothing like that has ever happened to me before. It was just so sudden and so intense."
Janice's husband Steff, also a manager and co-founder at Lanarkshire Paranormal, says: "It was probably about as active a night here as we've experienced.
"We've done Provan Hall three or four times now, and every time the activity we get - people being possessed, things like that - is standard for that place.
"We know someone is going to end up getting light-headed and being taken outside; we know someone will pick up on the ghosts of little children."
It was well after 3am when we finally emerged from Provan Hall, cold yet exhilarated. I'm willing to take bets that nobody slept with the light off that night. n
To join the next paranormal investigation of the South Lanarkshire branch of NAS at Govanhill Baths, Glasgow, on September 27, email email@example.com. Tickets cost £30. Visit lanarkshireparanormal.co.uk