Ma

It's formulaic and lazily constructed, but this psycho-thriller is given a much-needed lift by its star (and executive producer) Octavia Spencer. She plays a veterinary assistant traumatised by events in her teenage years, who befriends a bunch of high-school kids and allows them to use the basement in her remote country house for booze-fuelled parties. However, Spencer has her own agenda, and a murderous revenge plan takes shape. There are more laughs - unintentional or otherwise - than scares in the shaky proceedings, which build towards a suitably nasty pay-off involving Munchausen syndrome by proxy. Ma is a slick enough package from Blumhouse Productions (Get Out, Us), with Spencer's sudden lethal mood-swings generating the chills more than director Tate Taylor's awkward tonal shifts in atmosphere. Spencer previously won an Oscar for Taylor's The Help and it's another co-star from that movie, Allison Janney, who steals every scene here as her doomed boss.