It starts with a babysitter, always a young girl. The kids (she presumes) are upstairs, peacefully sleeping as she relaxes downstairs. Suddenly, there is a phone call. She answers the phone cautiously, and hears a strange man’s voice from the other end,
“Why don’t you go and check on the children…”
The creepy voice says. The babysitter slams the phone down and tries to take her mind off it, before the phone rings again.
This time laughing can be heard from the phone. Deep, ominous laughter. The now terrified babysitter calls the police to report the calls.
The police tell her not to worry, just a prank caller, some kid having fun…but that they will trace the call, just in case. And a few minutes later the phone rings again. The police.
“The phone calls are coming from inside the house.” The worried police man says, “Get out of the house as fast as you can,” 
But it’s too late. The man is already coming down the stairs. The babysitter screams, preparing for her tragic end…