In 1999, a fire inside the Mont Blanc Tunnel, the road link burrowed under the Alps between Chamonix, France and Courmayeur, Italy, killed 39 people trapped in their vehicles. This film reconstructs how a Belgian refrigerated truck caught fire roughly halfway through the 11.6-kilometer bore and why the blaze burned for two days, reaching temperatures high enough to melt steel. It walks through the tunnel's ventilation design, the emergency shelters spaced along its length, and the decisions made by control room operators and firefighters on both the French and Italian sides as smoke and carbon monoxide filled the passage faster than anyone had planned for. Engineers and investigators explain how a structure celebrated as a feat of postwar engineering, cutting travel time between two countries from hours to minutes, became a trap because of gaps between two national safety systems that were never fully reconciled. The film treats the disaster as a case study in cross-border infrastructure failure, following the inquiry that followed and the changes made to tunnel safety codes across Europe afterward.