very weekday morning a million commuters pour into the Sao Paulo metro, the world’s most crowded subway. This film follows the hard-pressed team of metro workers as they race against the clock to get everyone to work on time. Stunning CGI animation reveals how six key engineering inventions prevent this massive operation grinding to a halt. Overnight, a crack maintenance crew scans the track for faults using a technology more commonly used to scan pregnant women; as the trains start running, ingenious radio signalling replaces drivers, and squeezes more trains onto the track; at overcrowded stations, intelligent platform doors prevent crowd surges pushing people onto the rails; and to prevent a deadly fire, technicians fill a subway station with smoke to test Sao Paulo metro’s revolutionary smoke extractors. But will these modern devices do what’s needed to get a million commuters to work on time and enable the metro workers to beat the COUNTDOWN.