The remarkable success of Blumhouse Productions is built on making original horror flicks for $5 million or less, attracting unexpectedly big names to essentially stretch their legs and do some down-and-dirty genre stuff. Appreciating that there are few sights in cinema more enjoyable than someone well and truly working against type, the major coup for their latest, Ma, is in signing up Academy Award winner Octavia Spencer for her first lead role.

At the outset of the film, Su-Ann Ellington (Spencer) is perfectly maternal to 16-year-old Maggie Thompson (Diana Silver) and her friends. After buying them booze from an off-licence, she even offers her basement as a hangout spot for the group and their teenage pals to party away from the eyes of their parents and the cops. But as some uncomfortable home truths emerge about the woman they call “Ma”, Diana and her friends come to realise that they’re just pawns in a bigger scheme.

As with Neil Jordan’s recent schlock psycho-thriller Greta, there’s a definite sense of the script (which comes from Workaholics writer Scotty Landes) being elevated by the talent involved. Heck, there’s even a glorious but inexplicable extended cameo from Spencer’s fellow Best Supporting Actress winner Allison Janney, in a minor role as Su-Ann’s boss.

Director Tate Taylor has said that he took on the project after meeting with producer Jason Blum and expressly telling him that he wanted to make “something fucked up.” While the result is a bit vanilla for a horror film, it plumbs the premise for something deeper than you might anticipate from this sort of fare, while still revelling in the nastiness that goes with it.

Sitting proudly at the higher extreme of its 15 certificate, (as the BBFC guidance puts it, Ma “contains strong violence, sexual abuse, threat, sex, drug use, and very strong language”) the film builds up to an explosion of gruesome camp in its second half. Although Taylor’s previous film, the 2016 adaptation of The Girl On The Train, was undone by some of its tonal shifts, it’s fun to see how the same silliness suits this kind of hysterical B-movie material down to the ground.

In the thick of it, Spencer isn’t just delivering the Kathy Bates special, and the film does take time to probe her character’s backstory and explore some unexpectedly sympathetic ground. Looking at Spencer’s Oscar-nominated roles, it’s understandable that she’s itching to show off more of her range and while it’s incredibly unlikely that she’ll pick up many nominations for this, it’s really enjoyable to watch her work some different acting muscles.

Affecting a more doe-eyed performance than in her brief turn in the excellent Booksmart, Silver stands out among the generic gaggle of party-loving teenagers and bounces off Spencer’s implacable performance very nicely. Elsewhere, in addition to Janney, the adult cast is rounded out by Luke Evans, Juliette Lewis, and Missi Pyle, whose characters all land somewhere on the Roald Dahl spectrum of grown-up ghastliness as well.

Dressed up though it may be, Ma is an uproarious and eventually quite gruesome throwback (complete with 1970s disco soundtrack) that should keep schlock aficionados happy. As it ramps up, it gets messier and less character-focused, but it’s never less entertaining to watch. Having put the legwork into elevating the film early on, it makes an enjoyably bonkers descent into dark sight gags and cringe-making violence.

At a certain point, you’re going to realise that the guy who made The Help might have different ideas about what makes a film “fucked up” to most of us, but it’s competently made and there’s no faulting the enthusiasm of the unaccountably star-studded cast. While you definitely shouldn’t expect to be scared by it, there’s huge entertainment value in watching it spiral into madness as it goes on.