Investigative reporter Amy Klein (Kari Wuhrer) is sent to Bucharest at the behest of Charles (Simon Kunz), her boss, to investigate the origins of a video tape depicting the ritualistic murderâand subsequent resurrectionâof a member of a cult calling themselves "The Deaders". In Bucharest, Amy tracks down the return address of the VHS and discovers the corpse of a girl, named Marla, who had sent the tape holding a puzzle box, the Lament Configuration. Amy returns to her hotel and opens the box which summons Pinhead (Doug Bradley), although this is apparently all a dream. She visits some of the Bucharest subculture on a train where she meets Joey, who warns her about her the Deaders and notices that Amy has a 'self destructive thing'.
Amy pursues leads, ultimately tracking down Winter LeMarchand (Paul Rhys), the leader of the cult. Winter is the descendant of the toymaker who designed the puzzle box, which can open a portal to a realm populated by the Cenobites, hedonistic entities that experiment in forms of extreme sadomasochism. Winter believes that as the heir to the LeMarchand name, it is his birthright to access the realm of the Cenobites and become their master.
However, Winter has been unable to open the box himself. Believing that it takes an individual whose life circumstances have brought them to a nihilistic point beyond life-or-death, Winter founded the Deaders, attracting emotionally vulnerable individuals, murdering them, and resurrecting them with necromancy in the hopes of creating someone who can open the box. Winter kills and resurrects Amy, resulting in her experiencing an extended waking dream including a bloody bathroom scene and going to see Joey once again on the train. Amy also relives physical and sexual abuses from her childhood by her drunken, abusive father and young Amy eventually murdered him by stabbing him in the stomach with a large kitchen knife.
Coming back to reality in the Deaders' compound, Amy successfully opens the box and summons the Cenobites. Their leader, Pinhead, expresses disdain for Winter and his family and denies that any mortal could ever control the Cenobites. Pinhead and the Cenobites then slaughter all of the Deaders before indicating to Amy that she is now indebted to them by opening the box. Pinhead tells Amy her father has been waiting for her in the Cenobite realm. Rather than be taken back to the Cenobite realm, Amy kills herself by stabbing herself in the stomach with a large kitchen knife. After that, the box starts to close and an electrical charge surges out from the box, sending the Cenobites back to hell, and causing the house to explode.
Charles is watching a news report on the incident. Unaware of Amy's whereabouts, Charlie's secretary brings in a new female journalist and Charles talks about showing her a tape that might interest her. The film ends with the reporter holding up the Lament Configuration, which has been recovered from the collapsed building.

Question: What does the puzzle box open?
Answer: A portal.
Alternative answer: the Cenobites realm