The largely unknown British actor Sam Clafin has joined the cast of Pirates of the Caribbean: On Stranger Tides. Comingsoon.net are reporting that Clafin is to join the production as a young missionary who gets embroiled in the saga with Johnny Depp's Captain Jack Sparrow as he searches for the elusive Fountain of Youth. Clafin, who only has ten episodes of a show called The Pillars of Earth under his belt, will star alongside Depp, Penelope Cruz and Ian McShane on the blockbuster which is due out in the summer of 2011.