A couple left for a rare night out, leaving their two children in the care of their usual babysitter. The night was no different to any other, and by the end of the evening, both children were fast asleep in bed and the babysitter was comfortably settled down in front of the television.

Then the phone rang. The babysitter answered, but all she heard on the other end of the line was a sinister laughter. Figuring it was one of her friends playing a joke and trying to freak her out, she hung up, tried to forget about the call, and continued to watch the television.

Then the phone rang again. She answered. Nothing but the same maniacal laughter. Now she was becoming uneasy, but she once again ignored the call and tried to forget about it.

But after the third phonecall, she was far too unnerved to simply ignore the awful laughter and, figuring it's better to be safe than sorry, she quickly called the police.

The police assured her that it probably was just somebody playing a trick, but if the culprit called again, they would attempt to trace the call. All she had to do was keep the man on the line long enough for the trace to work.

She hoped it wouldn't come to that, and the phone would remain silent for the rest of the night. She was wrong.

When she answered the fourth call, she forced herself to remain on the line and listen to the laughter, knowing it was necessary. After a minute, the laughter began to quieten until the line went silent. There was a click, and the babysitter knew the line had gone dead.

Had he known what she was trying to do? Whatever the reason, she simply hoped that he'd waited long enough to hang up, that the trace had been completed.

Patiently she waited, and a few minutes later, the phone rang again. She answered and was relieved to hear the sound of a police officer on the other end of the line.

"Get out of the house," said the officer, "right now."

"What?

She was confused. What was he talking about? He seemed worried, but was trying to keep his voice calm and steady as he spoke to her.

"Get out of the house. Don't try to bring the children, just leave," he said. "The call is coming from inside the house."

When the police arrived at the house, they were too late.