The world’s longest cargo train runs from the Carajás mine in Northern Brazil across 900 kilometres of remote forest and grassland to the port of São Luís. It carries iron ore destined for China. This documentary follows the dynamic team of railway workers as they race against the clock to get the three kilometre-long train to the port on time. Dazzling CGI animation shows how six key engineering inventions prevent this colossal operation coming off the rails. At a giant silo, the load-out workers use an ingenious weighing system to load the ore into the train’s 330 wagons; once underway, the driver uses radio signals to harness the power of four locomotives spread along the train; to climb the railway’s steepest hill, the heavy train needs a push from a laser-guided locomotive; and to unload its 30,000 tonnes of ore, a rotary dumper must turn the whole train upside down.