An air of mystery surrounded Rosamund Pike in “Gone Girl” but there’s no mistaking her in “I Care a Lot.” Sporting designer suits and a bob cut so sharp that you tremble for her stylist, Pike’s Marla Grayson is ruthlessly imperious from head to toe. The title of J Blakeson’s sleekly sinister neo-noir is tongue and cheek. Marla, a shark on par with Gordon Gekko or Jaws, doesn’t care even a little. She’s a legal guardian to dozens of elderly people whom she bilks for everything they’re worth. A wall of their faces and names adorns her Boston office the way stock portfolios might a financier. “Playing fair is a joke invented by rich people to keep the rest of us poor,” she intones in the movie’s opening voice over. When so much real terror is stalking nursing homes, the timing of “I Care a Lot” (it debuts Friday on Netflix) is perhaps not ideal. Marla’s scheme is a particularly loathsome one, and the feeling of disgust only grows as writer-director Blakeson, the British filmmaker of the kidnap thriller “The Disappearance of Alice Creed,” depicts an interwoven system of elder abuse, with doctors and nursing home mangers all taking a cut. One of them hands Marla a “cherry” – an especially desirable new ward because she’s both wealthy and lacking any apparent living family that might interfere – in Jennifer (Dianne Wiest). A few falsified health records and a judge’s rubber stamp later, Jennifer is abruptly hauled off to a facility where her phone is taken and even straying outside is off limits. Marla and her partner-girlfriend (Eiza González), quickly start auctioning off her stuff. At this point, “I Care a Lot” seems poised to become another nightmare of wrongful institutionalization – a “Shock Corridor” for rest homes. Having Dianne Wiest locked up is no less infuriating than Jack Nicholson being strapped into a mental hospital. But the twists and turns of “I Care a Lot” lead elsewhere – in more comic, off-balanced but generally deviously delightful directions. Jennifer turns out to be not just a meek old lady living alone but the mother of a powerful and well-financed underworld figure with ties to the Russian mafia, Roman Lunyov (Peter Dinklage). Dinklage, as he often does, immediately recalibrates the movie, as Roman summons his forces – minions who cower before him while he snacks on an eclair or sips a smoothie – to free his mother.