There’s more pleasure than guilt in enjoying this guilty pleasure as director Tate Taylor collaborates with Octavia Spencer, his muse from The Help, for a memorable, against-type, unhinged performance in the psychological thriller Ma (B). When a lonely veterinary assistant starts opening her basement to a quartet of partying teens, it becomes clear something sinister is afoot in her drug and alcohol crazed makeshift speakeasy. In the spirit of Misery, Carrie or One Hour Photo, there’s a disturbing backstory to the central character’s plight and a method to the madness. Spencer nails the macabre mood swings of a character who longs to fit in with the in-crowd, and she brandishes a smartphone and ruthless cunning as weapons of choice. For every routine resolution, there’s also a disturbing detour, including some surprising props and prosthetics; and the sometimes preposterous story works as perverse entertainment largely because of the subversive nature of Spencer’s unflinching presence. The film practically begs for the call-back, “No. She. Did Not.” The teen actors including Diana Silvers and Gianni Paolo are authentic and engaging, and so are Spencer’s contemporaries including Luke Evans, Allison Janney and Juliette Lewis, the latter of whom has some satisfying echoes of her Cape Fear role. The chocolate icebox pie Taylor and Spencer served eight years ago has aged into a new mocha bonbon, a dish of revenge served cold by a woman scorned. By the time the film reaches its delicious denouement, you may find yourself grinning from the thrill and audacity of it all.