En route from Moscow to Perm, Russia, Aeroflot Nord Flight 821 is on its final approach when the plane nosedives and crashes onto the trans-Siberian railway. All that's left of the Boeing 737 is charred wreckage. All 88 people on board are confirmed dead. At first, investigators suspect a known design flaw in the aircraft's rudder. But as they dig deeper, they make a series of shocking discoveries that will result in calls to transform the country's aviation system.