Seven friends are on their way to attend a friends’ marriage when they see the aftermath of a car accident on the highway.

Former Scissor Gang leader Eun-jin (Shin Eun-kyung), who now suffers from amnesia, nevertheless defends Jae-cheol (Jun Gyu Park), a restaurateur who employs her, from a gangster who wants his business.

A staircase leading to the dormitory of a remote boarding school usually has 28 stairs, but every so often there appears to be 29. When someone steps on the mysterious…