Outside Seoul, surrounded by dense forests and quiet mountains, stood one of the country's oldest luxury hotels—The Ardent Hotel. It had been built in the late 1980s as an exclusive mountain retreat for wealthy families, celebrities and influential businessmen. Over the years, it became famous for its beautiful architecture, private gardens, enormous glass windows and peaceful location far away from the noise of Seoul. The hotel looked almost timeless. Dark wooden interiors, tall ceilings, vintage chandeliers and long carpeted corridors gave the place an elegant, slightly old-fashioned atmosphere. At the same time, the rooms had been renovated with modern technology, making the hotel a strange combination of old and new. Behind the hotel stretched a huge forest, while a narrow road connected the property to the nearest town. It was beautiful during the day. At night, it became almost completely silent. The hotel had six official floors, with guest rooms occupying most of the building. The ground floor contained the reception, restaurants, lounges and a large glass-covered garden. The basement housed staff facilities, storage rooms and an old service area that was rarely used anymore. Despite its reputation as a luxury destination, the hotel had always carried a few strange rumours. Some guests claimed that certain rooms occasionally appeared under different numbers. Others talked about hearing footsteps in empty corridors late at night or seeing lights switch on in unused parts of the building. The management always dismissed those stories as misunderstandings caused by the hotel's old structure. Most guests never thought much about them. The hotel had hosted countless weddings, business retreats, family vacations and private events over the decades, becoming a familiar getaway for Seoul's wealthy social circles.

This year, Haneul University selected the Ardent Hotel for a small weekend retreat.

A group of close university friends—you, Jungkook, Taehyung, Tzuyu, Jimin, Chaeyoung, Yoongi, Suzy, Hoseok and Wonyoung—decided to go together. For them, it was supposed to be nothing more than a few days away from lectures and assignments. A quiet mountain hotel. Good food. Late-night conversations. Long walks through the forest. And, most importantly, time together. None of them knew that the Ardent Hotel had a history far older than the rumours surrounding it. And none of them expected their weekend trip to become the beginning of something they would never be able to explain.

The hotel isn't simply hiding Room 707. Room 707 doesn't always exist. Sometimes the elevator goes from the 6th floor directly to the lobby. Sometimes it stops at 7. And every person who sees Room 707 sees something different. The first night, Jungkook sees an empty room.