He killed off clairvoyant Elise Rainier (Lin Shaye) too soon.
"She died in the first movie so it's not something where I could pick up from the first movie and continue with the adventures of Elise," Whannell told ABS-CBN News.
"I know I made a big mistake. What is wrong with me?" he said in a jest.
The chemistry between clairvoyant Elise Rainier and her not-so psychic sidekicks Tucker (Angus Sampson) and Specs (Whannell) has been a hit with the audience that the second and third installments either had to bring Elise back to life or tell a story when she was still alive.
The latest "Insidious" flick, "Insidious: The Last Key," is no different as Elise is well and alive in the film to deal with the paranormal.
"Seeing as I would have to go backwards anyway, I wanted to go right back to her story," Whannell said.
Despite the lopsided timeline of the flicks and its refusal to veer away from the life and adventures of long-dead Elise, the latest installment is kept somehow new with the addition of a love interest and another character who can see the unseen and wander into The Further.
"You still get all the scares and all the terror of an 'Insidious' film but hopefully there's a strong story there too - meeting her family, and finding out what they were like," Whannell said.
"Insidious: The Last Key" opens in Philippine cinemas on January 17.
source: news.abs-cbn.com
