Paranormal Activity 3 is a prequel to the first two movies in the Paranormal Activity franchise. The movie takes place in 1988 and focuses on the two sisters, Katie and Kristi, who are living with their mother and her boyfriend, Dennis.
Dennis is a videographer and he begins to record strange occurrences happening around the house, which he believes are caused by a supernatural entity. As he continues to film, the activity becomes more and more intense and violent.
Throughout the movie, it is revealed that Katie and Kristi have had encounters with the same entity when they were children, and that their mother had made a deal with the entity when they were young to protect them in exchange for a sacrifice.
As the activity in the house becomes more dangerous, Dennis and his friends attempt to find a way to stop the entity from harming the sisters. However, their efforts prove to be futile, and the movie ends with the entity seemingly getting what it wants.
Paranormal Activity 3 was a box office success, grossing over $200 million worldwide. It is praised for its effective use of found footage-style horror and building tension throughout the movie.