Rushing from the chaos of her student job, up the never-ending staircase of her apartment building, Danielle, a West African-French student, calculates that she has enough time to change from her work clothes before her final sociology exam in 20 minutes. Her under-maintained shoebox apartment has other plans. Yanis, a young concierge, comes to help and tries to fix the ancient door lock that has trapped her. As time trickles past, the two strangers find an unexpected solidarity, with only a door to separate them.