Director Lenny Abrahamson clearly has a thing about confinement and creepy obsessions. The titular character in his last film, Frank, played by Michael Fassbender, was a singer in an experimental band who walked around with his head inside a basketball-sized paper mache mask. Abrahamson’s new film, Room, based on the same-titled 2011 best-seller by Emma Donoghue, is about a mother (Brie Larson) and her son Jack (Jacob Tremblay) living for years in an underground cell in the backyard of a home owned by Old Nick (Sean Bridgers). I’m guessing that Nick (a) is Jack’s dad and (b) ravages Larson whenever the mood strikes. The trailer doesn’t supply particulars but that’s the basic shot. And then they escape. Donoghue may or may not have admitted that Room was largely inspired by the case of Josef Fritzl, an Austrian monster who kept his daughter confined in a cellar for 24 years (’84 to ’08) and fathered seven children with her, but it almost certainly was. By the way: Until you read the credits there’s no telling that “Jack” isn’t a girl — the teaser makes no effort to suggest he’s a young lad. I’ll see Room but I’m not looking forward to it. Who would?