MUMSY, NANNY, SONNY & GIRLY

Four individuals live in a secluded manor house in the English countryside, where they engage in an elaborate role-playing fantasy called The Game. In The Game, each individual assumes the role of a member in a "happy" family, completely subsuming his or her individual personality to the point that each individual is known only by the identity he or she is playing: Mumsy (the mother), Nanny (the nanny), Sonny (the son) and Girly (the daughter). The Game is built around a set of strictly enforced yet ill-defined rules, and the principal one is "Rule No. 1: Play the Game".

As a part of The Game, the teenaged Sonny and Girly regularly venture to more populated areas, where the pair use Girly to lure men back to the manor house. Once there, the men are dressed like schoolboys and forcibly indoctrinated into The Game, assuming the roles of "New Friends". Those who refuse are "sent to the Angels"—a euphemism for being ritualistically murdered in scenarios built around playground games, which Sonny routinely records on a 16 mm camera so that the family can enjoy the resultant snuff film.

One night, Girly and Sonny stake out a Swinging London party, where they encounter a male prostitute and his latest client. An instant attraction develops between Girly and the man, who convinces his client to accompany the siblings for a night of carousing. Girly and Sonny take the couple to a playground, where they murder the woman by throwing her from a large slide. The next morning, Sonny and Girly convince the hungover man that he murdered the woman after a night of heavy drinking, and they persuade him to return to the manor with them. The prostitute—rechristened "New Friend"—is outfitted in schoolboy clothes and subjected to an indeterminate period of torment "playing the game", during which he is repeatedly presented with his client's body as a reminder that the family has incriminating information about him.

After Mumsy makes sexual overtures to New Friend one evening, he gets the idea to turn the family against itself. New Friend's plot succeeds as he creates sexual jealousy between the women after first sleeping with Mumsy and then Girly. Sonny, left out of the sexual politics, petitions to have New Friend "sent to the angels"; in a moment of panic, Girly bludgeons Sonny to death with an antique mirror. Chastising Girly for creating a mess, Mumsy dismisses Sonny as "naughty" and orders a visibly shaken New Friend to bury Sonny beneath a drained fountain on the manor grounds, which is populated by makeshift gravestones bearing the numerical identities assigned to dispatched "friends".

Nanny, jealous that she is the only female member of the household left out of New Friend's attentions, attempts to murder Mumsy with an acid-tipped needle, but the attempt fails when it is inadvertently interrupted by New Friend. Girly, realising that Nanny has set her sights on New Friend, hacks Nanny to death with an axe. In the kitchen, Mumsy finds Nanny's head cooking in a pot and Girly sings "When she's dead, boil her head, make it into gingerbread".

Mumsy and Girly declare a truce, deciding to "share" New Friend by alternating which days of the week each of them will be permitted to have sex with him. They ponder what will happen should either of them become bored with him, which Girly declares is an inevitability. Overhearing their conversation, New Friend retrieves Nanny's acid-tipped needle and, lying smiling on Mumsy's bed, hides it under the pillow.

The film climaxes with Girly killing Sonny during a dispute, followed by Mumsy ordering New Friend to dispose of the body. Further attempts at murder ensue, with shifting alliances as the household's power dynamics unravel.

The conclusive acts of violence expose the instability beneath the family's rigid game structure, with each character vying for control and survival. The ending reflects a collapse of their constructed reality—no one is immune to the chaos they've created. It's a pointed commentary on repression and the destructive potential of enforced fantasy.