An ordinary family in an average neighborhood: a mother, a father, and a daughter who had just turned sixteen.

  Melissa was at that age when many feel the need to experience new emotions.

  It’s a complicated stage. The danger lurking outside isn’t always easy to recognize.

  There are pleasant things, sure—but they can be easily confused with risky situations. And without the maturity to tell the difference, it's hard to know how to face them.

  Almost all teenagers go through similar processes, but not all of them are the same.

  María was Melissa’s best friend and classmate. For some time now, she had started acting strange.

  They used to be inseparable, known for their contagious laughter and radiant energy.

  Whether they were talking about boys or presenting a project in class, both stood out with their wild sense of humor and uncontrollable giggles—even the teachers couldn’t help but laugh with them.

  But little by little, María stopped being that vibrant girl.

  Her teachers and classmates began to notice.

  Whispers floated through the hallways: “What’s wrong with María?” or “She’s not the same anymore…”

  Melissa, however, didn’t brush it off. She was truly worried.

  She tried to talk to her whenever she could, but María would just stare back coldly, as if she were no longer the same person.

  Melissa even went to her house several times, but María’s parents always gave short, evasive answers.

  The last time, something inside her screamed, “Something is very wrong here.”

  Frightened and frustrated, she went to the school principal and the math teacher—sisters, both in charge of the institution—and begged them to do something. They agreed.

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  María had already been absent for three days and wasn’t answering any calls.

  On the fourth day, Isabel (the principal), Sandra (her sister), and Melissa went to the house.

  They knocked on the door for several minutes. No one answered.

  They decided to call the police.

  But Melissa’s dreadful feeling was too strong. She stepped forward… and the door creaked open.

  The two women, filled with fear and uncertainty, followed her inside.

  What they found was a horrifying scene.

  There was blood everywhere.

  In the kitchen lay the bodies of María’s mother and older sister—brutally stabbed.

  Suddenly, a buzzing sound—like the whistle of the wind—came from the second floor.

  Melissa and Isabel ran upstairs. Sandra, her hands trembling, tried to call emergency services.

  Blood stained the stairs, and the walls, leaving a trail.

  “María! María!” they shouted into the darkness.

  A half-open door. Melissa, shaking, pushed it open. It was the room of María’s younger brother.

  Inside were his body—and the father's. Both had been slaughtered, their throats slit.

  Only one place was left to check: the parents’ bedroom.

  There, on the bed, they found María. She was covered in blood, with deep cuts on her forearms.

  Melissa couldn’t understand what had happened.

  Her cries echoed throughout the neighborhood.

  The police sealed off the area. Neighbors crowded the street.

  Isabel and Sandra were in shock.

  Melissa, silent, could only think of the happy memories of her friend.

  The police reports concluded that María had gone mad, murdered her family… and then taken her own life.

  The school declared three days of mourning.

  But it was far from over.

  Weeks later, another tragedy: Principal Isabel lost her mind, killed her sister Sandra, and then committed suicide.

  Melissa never recovered.

  She claimed to hear a constant buzzing.

  She insisted someone else had been in that house that day.

  Terrifying images haunted her mind, and she was admitted to a psychiatric facility.

  Neither medication nor therapy could calm her.

  Her thoughts repeated over and over again…

  Who else was in that house?