There is absolutely no doubt that the artists of American dance theatre company Pilobulus are supreme masters of the ancient art of shadow play.
They catapulted to fame, largely on the strength of an award-winning car commercial and their riveting performance of shadow clips for all the films nominated for Best Picture at the 2007 Academy Awards.
But Shadowland, already seen by half a million people worldwide, is their first feature length production made almost entirely in shadow.
No one could fault the technical prowess involved in perfectly performing a 90-minute stretch of eye-boggling and jaw-dropping images, extraordinary bodies honed and held in incomprehensible exactitude to create the plethora of amazing creatures that inhabit the work.
But in spite of the action, the cleverness, the extraordinary athleticism, the dark and somewhat primal power of their creation, 90 minutes does begin to seem, around the 60-minute mark, something of a marathon.