Like every weekend, nineteen-year-old student Rachel is babysitter to the two-year-old baby Hugo. When Hugo's single father has gone out for the night, Christine takes advantage of it to invite her good friend Christine.

A teenager discovers the first stirrings of love. Her daily life unfolds in a stairwell. It is there that she leaves her boyfriend before going home; it is also there that she meets her girlfriend. It is there that the powerful emotions of her young life play out.