The Mont Blanc highway tunnel that links Italy with France is one of the longest vehicle tunnels in the world. On March 24, 1999, a 40 ton truck carrying flour and margarine caught fire in the middle of the tunnel, and turned the tunnel into an inferno. The aftermath left at least 38 motorists dead. Motorists speak of what they witness that day. And firefighters provide insights of their fire fighting efforts. Using data from investigators, the cause and events of the disaster are piece together. The results are then presented to viewers with the help of advanced computer graphics.

A subterranean infrastructure of sewers, telecommunications, electricity, and water keeps every modern city alive -- and is taken for granted until something goes wrong. On April 22, 1992, in Mexico, something went very wrong.