This documentary is about Tian Tong Yuan, which is called "the largest community in Asia." It has a large floating population. Housing problem is extremely serious as many people live in room-sized areas in the basement. The director of this movie rented a room and experienced the life of these people.天通苑,這個坐落於北京北五環外的巨型社區,像是一個龐大而繁雜的迷宮,被人稱為“亞洲最大的社區”。天通苑擁有三十多萬固定人口及相同數量的流動人口,是北京群租房現象最嚴重的社區。導演住進地下群租房,親身體驗這裡的生活。影片講述了幾位外地大學生在北京謀生的故事。