Two boys are recording their experiences in a strange, abandoned psychiatric hospital in Toronto. Rumor has it that the table-tennis loving hospital director suddenly killed all the patients and disappeared. The two boys head towards the room with the intensive care unit, ie room number 401. No one could open this room before. They try to open the door but suddenly a table tennis ball is heard. Their broadcast ends abruptly but not before catching a glimpse of the ghostly face. Upon hearing of the disappearance of the two teenagers, Andy Shaw, the owner of a YouTube channel called Horror Chronicles, decides to investigate and explore the asylum.
Andy finds a group of six people: three girls: Chloe, Rachel and Lucy; And three boys: Kevin, Victor and Carlos for the live broadcast. Andy stops at his base camp off the road to control the broadcast while the rest of the group moves in. They tie underwear to a tree as a marker. Inside, Rachel pours holy water into a small vessel to record her reactions. In the director's office, they find a group photo with all the patients and staff, and Lucy and Rachel find a doll in the lab, which they later learn has gone away on its own. They see that it is the same doll as a patient held in the group photo.
Carlos and Chloe try to open the door to Room 401, while the other four explore the "Group Treatment Room", where there are several strange coffins with holes in them. When Lucy puts her hand in a hole, her hand is pulled out and injured. Upset, Lucy and Rachel decide to leave. Andy reviews the footage of all six participants standing together and becomes perplexed, not sure who filmed it if all six were in the shot. Outside, Rachel and Lucy encounter underwear markers more than once, revealing that they are going in circles somehow. Lucy goes into a trance and her eyes turn completely black. Frightened, Rachel flees to base camp but finds herself sheltered in Room 401. Lucy is in a corner with the doll. A naked man appears and Rachel is attacked and dragged into the darkness.
Victor and Kevin see a wheelchair moving by itself in the basement. Everything in the room starts to float, and the two boys make their way out of the flying objects. Victor wakes up and is dragged by an invisible force. Kevin wakes up and runs to Carlos and Chloe, who are still trying to open the door to the 401. Kevin informs them that the show was meant to be scripted, but real paranormal forces have attacked them and they need to save Victor. Suddenly, a table-tennis ball bounces towards them and Rachel's scream is heard from inside the 401. Infra-red cameras start flashing to detect a presence. 401 opens and the screen goes dark.
Kevin, Carlos and Chloe find themselves in a dark room with no exit, standing in knee-deep water. Innumerable ghosts appear and they are possessed one after the other and vanish into darkness. Andy, seeing his view count reach nearly 1 million views, goes to investigate and is strangled to death. The last one, Victor, finds himself wheelchair bound and is the last one to be pulled into Room 401.
We later learned that despite everyone's continued airing, Kevin admitted that the livestream was actually cut after the stream was scripted. The audience, none the wiser, scoffs at the failed stream. Additionally, the number of views did not reach anywhere near 1 million (despite what Andy saw on his monitor), and only 503 views were reached. Later the pot of holy water starts boiling.
