It's hard to even call them family, as such. Only one child, the severely brain-damaged Angela (Miciah Dring), is their own. The others are kidnapped additions brainwashed into adhering to the family's rules. These are vindictive Birdie (Ainsley Howard) and her silent "brother," Elby (Toby Alexander). It kind of reminds me of the 1970 horror film Girly, in which "new friends" are brought forcibly into a family of depraved Brits, If Girly were applied with the visceral brutality of a blunt hammer.
The newest addition is quiet Polish immigrant Lena (Olga Fedori), who meets the loquacious Birdie at the airport where they both clean. Lena isn't stupid; she's just awfully polite -- too polite to follow her instincts. When Birdie and Elby "accidentally" make Lena miss her bus, she goes home with them, against her own better judgment.
Enter "Mum and Dad" (Dido Miles and Perry Benson). Mum is a manipulative, slick sexual deviant. Dad is also a deviant, who hits Lena over the head and rapes raw meat in front of his family (the camera then closes in on the cum in the meat *gags*). It's the kind of family relatively normal people stay away from, and Lena is not only determined to survive, but to escape.
To remain free of all pretenses, I will just call a spade a spade -- this is a torture flick, competently executed, but mostly devoid of any higher purpose, deeper meaning, or pathos. It does sport, however, an intense and cleverly executed ending and decent acting (best from Dido Miles, who plays a soft-spoken psychopath so well). As a note to people who, like myself, can stomach graphic violence but have trouble with sexual assault, there are no rape scenes in this film, although sexual perversion is prevalent.
Lena is a likable heroine, and although she certainly doesn't bring about fascination, the viewer will want to see her through. The film is primarily set in the home of the killers, with shots of airplanes soaring overhead, conveying a feeling of distance and one's desperate need of rescue going unnoticed. Now that I have called a spade a spade, I recommend Mum & Dad to extreme horror buffs and those with (very) strong stomachs.