少女Rachel接触到社交网络爆火的“墙中人召唤”挑战：只需在暗室中邀请 “住在墙里的人” 现身，就能唤醒墙中蛰伏的存在。她和好友尝试后，不仅释放出人形与畸形怪物，更引发连环失踪与猎杀。三个参与挑战的青少年，必须在怪物彻底失控前将其送回墙壁，而父母的完全不信任，让他们只能独自面对这场绝境危机。

yle=color: rgb(17, 17, 17); f>Rachel is introduced to a viral craze of allowing people who living the walls out into the world. This ends up badly and when her parents don't believe her two kids from her school do as they attempt to fight back against these creatures.