In the episode 4x15 of the TV show "The Vampire Diaries," titled "Elena breaks down and turns off her humanity," the main character Elena experiences a traumatic event that leads her to shut off her emotions.

This decision to turn off her humanity has significant consequences for Elena, as well as those around her. The episode delves into Elena's internal struggles and the impact of her actions on her relationships with others. Throughout the episode, viewers witness Elena's descent into darkness as she grapples with her new emotional state. 

This pivotal moment marks a major turning point in Elena's character development and sets the stage for future conflicts and plot developments within the series. Overall, the episode highlights the complexities of human emotions and the consequences of suppressing them, providing viewers with a dramatic and engaging storyline to follow.