Between the layers of the city lies a fragmented memory, that of the first hip-hop dancers in Châtelet-Les-Halles. Through the testimonies of key figures – Koïsso, Jean-Claude Guibert, Marguerite Mboulé and DJ Chabin – Sous le béton brings to life the gestures, voices and trajectories of this first generation of urban artists: a lost heritage, buried beneath successive renovations and the absence of archives.