Insidious: The Last Key is the fourth instalment of the franchise, but it’s actually the sequel to a prequel. If you wish to watch these movies in chronological order order then 3, 4, 1, 2 is the correct sequence. However, it is not essential to be au fait with the lore of the series to follow the plot of Insidious: The Last Key, although there are a few in-jokes for fans. The film begins with a prologue that gives us the backstory of Elise (Lin Shaye), our psychic who protagonist. Her childhood is far from happy as she lives next to the state prison where her abusive father is the executioner on death row. Young Elise and her brother encounter several paranormal incidents, the last leaving Elise possessed. Her mother Audrey rescues her but dies in the process. The film then moves on to 2010, where Elise gets a call from a scared man currently living in her old house. Despite reservations, she agrees to meet him and confront the supernatural forces behind the haunting. Her two assistants, Tucker (Angus Sampson) and Specs (Leigh Whannell), accompany her and encounter a growing series of well executed but somewhat formulaic set-pieces.