The Hellbound Heart

Synopsis

Frank Cotton is a hedonist who has devoted his life to a selfish, single-minded pursuit of the ultimate sensual experience. Believing he has indulged in every pleasure the world can offer, Frank is left unfulfilled and wanting for something more extreme. He hears rumours of the Lemarchand Configuration, a puzzle box that is said to be a portal to an extradimensional realm of unfathomable carnal pleasure. Locating the owner in Düsseldorf, Frank obtains the box by performing "small favors" and returns with it to his deceased grandmother's home in England. Frank prepares a shrine of offerings for the realm's inhabitants: The Cenobites, members of a religious order dedicated to extreme sensual experiences.

Opening the box, Frank is confused and horrified when the Cenobites, rather than beautiful women, turn out to be horribly scarified creatures whose bodies have been modified to the point that they are apparently sexless. Nonetheless, Frank eagerly takes their offer of experiences like he has never known before, despite their repeated warnings that it may not be what he expects and that he cannot renege on their agreement. With Frank as their newest "experiment", the Cenobites subject him to total sensory overload, at which point he realises that the Cenobites' devotion to sadomasochism is so extreme that they no longer differentiate between pain and pleasure. Frank is sucked into the Cenobite realm, where he realises that he will be subjected to an eternity of (what is to humans) torture.

Sometime later, Frank's brother, Rory, and his wife, Julia, move into the home. Unknown to Rory, Julia had an affair with Frank a week before their wedding; she has spent the entirety of her marriage obsessing over and lusting after Frank and has only stayed married to Rory for financial support. While moving in, Rory accidentally cuts his hand and bleeds on the spot where Frank was taken by the Cenobites. The blood, mixed with semen that Frank had ejaculated onto the floor before he was taken, opens another dimensional schism though which Frank escapes. However, his body has been reduced to a desiccated corpse by the Cenobites' experiments. Julia finds him and promises to restore his body so that they can renew their affair.

While Rory is at work, Julia begins seducing men at bars and bringing them back to the attic, where she murders them and feeds their bodies to Frank, whose own body begins to slowly regenerate. Kirsty, a friend of Rory's who is secretly in love with him, suspects that Julia is having an affair and attempts to catch her in the act; instead she encounters Frank, who attempts to kill her. Kirsty steals the puzzle box and flees the house, collapsing from exhaustion on the street. She is taken to a hospital, where she solves the box and inadvertently summons the Cenobites. The Cenobites initially attempt to take Kirsty back with them, until she tells them about Frank; skeptical that one of their experiments could have escaped, the Cenobites agree to leave Kirsty alone in exchange for Frank's return.

Kirsty leads the Cenobites to Frank, now wearing recently slain Rory's skin. Another altercation ensues, during which an unrepentant Frank inadvertently kills Julia. Assured of Frank's identity, the Cenobites appear and ensnare Frank with a multitude of hooks and return with him to their realm. Downstairs, Kirsty sees Julia's disembodied head calling for help, which is apparently unsuccessful as the Engineer's bright head appears under her veil (implying that they are dragging her too). Leaving the house, the Engineer bumps into Kirsty, entrusting her to watch over the box until another degenerate seeks it out. Looking at the lacquered surface, Kirsty imagines that she sees Julia and Frank's faces reflected in it, but not Rory's. She wonders if there are other puzzles, that might find a way to where Rory resides by unlocking the doors to paradise.