The film \"Insidious: The Last Key\" unfolding immediately after the events described in previous parts of the series. In the Centre of the story turns out to be Alice Rayner, a woman who all his life took a psychology. But at some point she realized that understands not only the living but also hears sounds dead. Trying to make sense of their abilities, Alice realized that can communicate with those who have long been gone from the world of the living. At first she was scared of his abilities, but then she managed to learn to control them and send in the right direction. Alice then began to help those who are concerned about the evil entity.
The main character went through a lot of trouble. She drove more than once aggressive perfume wafting into our world, and saved many lives. Alice remembers his youth when she only discovered the unique ability. While living in New Mexico, she has become hostage to the evil demonic spirit who settled near her house. He threw her a challenge, trying to turn her life into a nightmare.