The story of The Threshold spans over a few centuries, revolving around a mysterious house and its alleged secret treasure. The original owner is obsessed with the house, but once he enters it, he never leaves, till his death. Over a century, a creepy urban legend develops about it. But nobody tampers with it till a real estate mogul wants the property to build a business tower on the site. To gain legal control over it, he strikes a deal with the city officials, and starts a reality show in which contestants are asked to enter the house and retrieve the treasure from it. The show does not go as planned, and the newly built tower will hold deadly secrets of its own.