Motorcycle stunt-riders perform death-defying tricks in state-of-the-art 3D. Risking life and limb by way of bikes, trikes, buses, motorcycles and semis-these are the things of Nitro Circus, and therefore this movie. Led by Travis Pastrana, Nitro Circus got its start back in the early 2000s when a collective of extreme sport buds started cranking out DVDs of their back-flipping, tumbling, face-in-the-dirt engine-propelled stunts.