In the aftermath of the fire that struck Notre-Dame de Paris in 2019, the cathedral is in danger of collapsing. A race against time begins for a hundred men and women who will face danger, the unknown, and toxic lead dust for a year to save this world heritage site. Architects, stonemasons, carpenters, crane operators, scaffolders, rope access technicians, archaeologists: this unique project brings together rare skills. With rare enthusiasm and cohesion, they will achieve numerous technical and human feats. This film recounts the spectacular and moving adventure of these builders fighting to save Notre Dame.