A building lost in the midst of a 5 000 hectare park, that’s the equivalent of the surface of Paris, Chambord is the castle of all superlatives. 156 metres of façade, over 400 rooms, 77 stairways. The castle commissioned by François 1st in the 16th century is also the most mysterious. For over 5 centuries, its design has aroused curiosity. All the plans and archives relative to the building works were mysteriously destroyed in a fire… Does Chambord have a secret to hide? The question is all the more relevant as at the time of the castle’s conception, the greatest genius of the Renaissance was working for the King of France. That genius was no other than Leonardo da Vinci. Exactly what was his role in Chambord? From the use of revolutionary techniques to the extraordinary central stairway, what proof is there of the Italian genius’ involvement in the castle’s design? Does Chambord have a hidden meaning? With this documentary, we’ll take you into the heart of a scientific enquiry. By means of a 3D Scanner, an X-ray machine, and archaeological digs, the most renowned specialists will scrutinize the castle to try to shed light on a secret that’s been hidden away for 500 years.