The Mauritanian.The film, which is being produced by SunnyMarch – an independent film and television company that Cumberbatch jointly owns – explores the experiences of Mohamedou Ould Slahi who was incarcerated at Guantánamo Bay for 14 years without charge.After the 9/11 attacks in 2001, the offshore prison camp in Cuba was set up to hold suspects relating to terror charges.