Insidious Chapter 3

The law of diminishing returns is in full effect with “Insidious: Chapter 3,” a mediocre follow-up to the half-decent sequel to the quite-good 2011 horror flick.

This one’s a prequel, actually, focusing on a teenager named Quinn (Stefanie Scott) who has a near-death experience and is thereafter haunted by something in the apartment building where she and her father (Dermot Mulroney) and irrelevant little brother live. Veteran workhorse actress Lin Shaye, committed as always, returns as Elise, the psychic who says she’s out of the seance business but reluctantly helps Quinn. Screenwriter Leigh Whannell, in the director’s chair for the first time, delivers a scant few shocks and shivers with his unimaginative take on a tired formula, and doesn’t add anything to the Insidious “mythology,” either. Get some fresh ideas or let this series die.

C (1 hr., 37 min.; PG-13, some profanity and scariness, nothing too heavy.)