A teenage girl is babysitting at night. The children have been put to bed upstairs and the babysitter is downstairs, watching television. The phone rings; the caller tells her to "Check the children." The adolescent dismisses the call and goes back to watching television. The anonymous caller dials back several times. Eventually the babysitter calls the police who inform her they will trace the next call. After the stranger calls again, the police return her call, advising her to leave immediately. She evacuates the home and the police meet her. They explain that the calls were coming from inside the house, and that the unidentified prowler was calling her after massacring the children upstairs.

Other variations of the same story:

1. The caller turns out to be either one of the children or by an elder sibling who decided to scare the babysitter as a prank. But they get told off by the police.

2. The children are with the babysitter while watching the television. The phone starts ringing and a manic sounding man says that he will be there in a certain amount of time. He continues to periodically call as the hour draws closer, his voice becoming more and more hysterical. The babysitter gets scared and dismisses the possibility of a prank call and phones the police. After they get the news that the calls are coming from inside the house, they hear a door upstairs opening and then the sound of footsteps heading towards them. They run out of the house and the police arrive just in time.

3. Another variation involves two babysitters. After the first girl learns from the operator that the calls are originating from the upstairs extension, she runs to the stairway to summon her friend. As she approaches the stairway she hears a thumping sound coming from the stairs — the sound of the friend, her limbs severed, dragging herself down the stairway. (In some versions the mutilated friend warns the first babysitter that the children have all been murdered and urges her to flee the house.)

Teenagers have been scaring each other silly with this urban legend since the late 1960s, though most people nowadays are probably more familiar with it as the plot of the 1979 horror film When a Stranger Calls (or the 2006 remake of the same title). It's not based on any real-life incident, so far as anyone knows, but the scenario is plausible enough to give goosebumps to anyone with a sense of what it's like to be young and inexperienced and alone in a big house caring for someone else's children.

"The most frightening aspect of this legend is that the babysitter is not in control at any time," writes folklorist Gail De Vos. "The caller multiplies the anxiety that the babysitter is already feeling as the responsible person in the household. The possibility that this could actually happen is never far from the mind of any babysitter."

Never mind the unlikelihood that police would be able to trace a phone call that lasted no more than 20 seconds at most, or that an officer could be dispatched to the house so quickly. Albeit framed as a cautionary tale, the main purpose of the story is to frighten us, not give us actionable information. That it's still going around some 40 years later is a testament to how successfully it accomplishes its goal.

Its obvious features deal with the insecurity felt by adolescents as they are required to accept increasing responsibilities while making the transition to adulthood. The teenage girl is not simply left alone to fend for herself, but she is also made responsible for the safety of other children (in what might be considered a “dress rehearsal” for motherhood). She fails at her task in the most catastrophic manner (with the implication that she is at least partly to blame for being too absorbed in watching television), and, in a delicious irony, she herself is threatened through the instrument that is a teenage girl’s favorite means of social communication.