The ambitious Aneesh Cheganty, who directed the elegant and engaging cyber-mystery Searching, loses steam in the sprint of his sophomore effort, Run (C+), a decent PG-13 starter horror movie for tweens but hardly new territory for anyone else who has seen a feature film before. The timing is pretty prescient for a lockdown thriller, but the result here is muted and mixed. Run is greatly enhanced by the presence of glorious newcomer Kiera Allen, an intuitive and expressive actress whose home schooled character is confined to a wheelchair while living with a controlling mom played with campy ferocity by Sarah Paulson. Much of the mystery revolves around this relatable heroine finding out facts while her mother is away for very brief spells, which is a taut and terrifying device until it is not. A fairly mesmerizing first act devolves pretty rapidly thanks to some far-fetched plot devices and surprises you can anticipate without a doubt at each corner. Allen’s character is so ingenious most of the time that it’s a wonder she gets thwarted Coyote and Road Runner style as many times as she does when the screenplay needs to level the playing field. See Ma, Misery or the original Carrie for a far more absorbing take on this type of “crazy lady in the cabin in the woods” material. It’s never a good sign when you say to yourself, “Well, I guess this could be seen in a way as a guilty pleasure.” Cheganty is a talented director undone in this case by a script that doesn’t measure up. He earns his steps for most of the effort but stumbles when it matters most.