The echoes of departed spirits often show up on camera when those in shot were unaware of their presence.
But, as this spine-chilling video shows, sometimes the undead are more than capable of making their presence felt.
It purports to show the startling moment that a phantom pushes a man to the floor before seizing hold of his leg and dragging him along a deserted corridor.

But just as it seems the demonic entity is about to drag its no-doubt accursed victim to the deepest pit of hell, it lets go and vanishes, as mysteriously as it appeared.
The minute-long clip, which emerged online, shows footage of unknown provenance shot on a CCTV camera which captures a hoodie-wearing gentleman striding purposefully along a deserted corridor.

With few signs of life in the stark, clinical-looking corridor, it is already an eerie scene, but hardly looks like the kind of place where the dead might visit.
The clip is silent, presumably since the surveillance camera on which it was shot has no microphone. As the man reaches the end of the corridor a forbidding shadow-like apparition materialises ahead of him.

The terrified victim is continued to be dragged across the ground by his foot

His previous confidence evaporates as he is knocked to the ground by the spectral assailant. Before he can react, it snatches hold of his left leg, dragging him along on his back.
The victim of the supernatural attack, whose identity is not known, must have thought his days were numbered. He may have feared he would spend the whole of the rest of eternity in a pit of hellfire.
But without warning, the wraith relinquishes its grip and, as quickly as it materialised, it dissolves.
Terrified, its victim, scrambling to his feet, flees in the very direction he has just come from.

The video’s origin is unknown, but it has made its was to YouTube where it has received nearly a million views on one channel.
Commenters were mixed in their opinions as to its authenticity.
Cassandra Jordan wrote that she fell victim to a similar supernatural attack as a teenager. ‘I saw this dark entity looking at me with red eyes,’ she wrote.

Not looking back, the victim, caught on CCTV, continues to run for his safety
‘I tried to run but it grabbed me and dragged me back in my room. I passed out i didn’t know what happen after that all I know is that I wake up running to my older sister and scratching her uncontrollably.’
But others dismissed it as a ultimately flawed attempt at amateur computer-generated imagery.
Mongodos wrote: ‘Hey good attempt at cgi. Salute. I would recommend to change your filter and look at the floor. The floor lighting is not distorted. You did the wall well, but pay that in mind on the next attempt.’