She is in Danger [封口者]

When Luo Xue runs away in anger from her boyfriend, she unwittingly stumbles upon a murder case committed by a pair of harmless-looking young boys and girls. Fearing that word will get out, the secretive pair imprison Luo Xue in the attic. As Luo Xue's "best friend" Su Wen intervenes, things become more and more unpredictable and the truth gradually emerges