With the Insidious canon, the writer-producer team of James Wan and Leigh Whannell are building another franchise along the lines of their time-bending Saw series. Having established an intriguing multiverse for Lin Shaye’s homebody psychic to investigate in 2013’s second instalment, this prequel makes an entirely decent fist of a story about a bedbound teenager (the bright, sympathetic Stefanie Scott) attracting demonic interest after reaching out to her late mother. Whannell, making his directorial debut, does a solid job in assembling the nuts and bolts of his own script, loyally bumping up Shaye’s screen time while fashioning some pleasing, suspenseful sequences tracking the demon’s heavy-tar footprints through the Scott household. The envelope remains resolutely unpushed, and the need to function as a multiplex scare-machine precludes the emotionality of The Babadook. Yet, with its slowburn reveals and leftfield jolts, it’s been more carefully constructed than most series’ third chapters.