The creepy footage shows Louise Lenton’s five-year-old child doing laps around the car park in front of Oldway Mansion, in Paignton, Devon.
Around 17 seconds into the clip, the boy can be seen riding towards the front door of the building.
The camera then captures a ghostly figure watching his every move from a first-floor window.
It appears to be wearing a period outfit with a white shirt.
The clip – filmed on Sunday evening – has left Louise stunned.
“It wasn’t until I was home and in bed watching the film back when I noticed it,” she told Devon Live.
“I was like ‘oh my gosh!’ and my partner could not explain it. Neither of us know what this is.
“When I was filming I didn’t see it at all, I was too busy filming. I screenshotted it and zoomed in straight away.
“It looks like a lady with hair in a bun, with white cuffs around her hands.”
Louise has even approached Torbay Council about the mystery figure, who said only security guards would have been inside the building when the footage was taken.
Ghost at Raynham Hall, Norfolk
But the mum dismissed those claims, saying the “Victorian” outfit of the “woman” suggested it was something else.
Since the clip has gone viral, Twitter users have speculated the figure could be tragic dancer Isadora Duncan.
Isadora died in 1927 after a silk scarf she was wearing caught around the wheel of an open top car, breaking her neck.
She was believed to have had an affair with millionaire Paris Singer – the son of the man who built Oldway Mansion.