A group of crazies tries its hand at social engineering in “1BR,” a claustrophobic thriller set in a Los Angeles apartment complex whose evils the sun never comes close to disinfecting.

For Sarah (Nicole Brydon Bloom), recently arrived in Hollywood with plans to become a costume designer, her new home seems idyllic. The upbeat manager (Taylor Nichols) has chosen her over dozens of applicants, and her handsome neighbor (Giles Matthey) is almost uncomfortably solicitous. The other residents can’t do enough for one another, sharing barbecues and loving concern for the aging actress (Susan Davis) who appears to be everyone’s favorite.