 In 2009 Grierson was invited to the "Avatar" set during shooting by James Cameron, and was selected to direct a 3D cave-diving drama "Sanctum", using the Cameron-developed Fusion Camera System.The script is inspired by the near-death experience of one of the writers, Andrew Wight, who was trapped in a cave collapse under the Nullarbor Plain.It was shot at Warner Roadshow Studios on the Queensland Gold Coast, and the film opened 4 February 2011.