A group of high school friends are hanging out online one evening, using a popular video chat software to communicate. The group includes Blaire, her boyfriend Mitch, and their friends Jess, Ken, and Adam. Their seemingly normal conversation takes a dark turn when an anonymous user joins their chat. Initially unable to figure out the identity of the intruder, they assume it's a glitch or a hacker. However, the mysterious participant soon reveals they have intimate knowledge of the friends, specifically surrounding a shaming video of their classmate Laura Barns, who committed suicide as a result of cyberbullying. The conversation escalates as the anonymous user begins to expose secrets among the friends, leveraging their past actions and guilt over Laura’s death.

Tension mounts as the group is forced to confront the consequences of their behavior online and the nature of their friendship is tested. The anonymous user's demands become increasingly menacing, revealing that their motive is tied to seeking vengeance for Laura's humiliation and death. The friends are coerced into playing a sinister game that punishes them for lying or attempting to disconnect. As they desperately try to identify the anonymous user and find a way out of the situation, they are faced with the terrifying reality of their actions coming back to haunt them, challenging the very fabric of their relationships and their sense of morality.