Paul Bettany has pulled out of Showtime’s drama pilot Masters of Sex. The British actor was to play 1960s human sexuality pioneer William Masters in the project, an adaptation of Thomas Maier’s book Masters of Sex: The Life And Times Of William Masters And Virginia Johnson, The Couple Who Taught America How To Love. It chronicles the lives, romance and pop culture trajectory of Masters and Johnson, whose research touched off the sexual revolution. This was going to be Bettany’s American series debut and was considered a coup for Showtime and series producer Sony Pictures TV, especially given The Beautiful Mind co-star’s known difficulty to commit to projects. He recently passed on several big roles, including the lead in The King’s Speech, which earned Colin Firth an Oscar. Complicating things on Masters Of Sex was the fact that Bettany had a say in the casting of the female lead, which had stalled the process. The pilot will now launch a new search for both leads, with Lizzy Caplan talked about for Johnson. Michelle Ashford wrote the script for Masters Of Sex and is executive producing the pilot with Timberman/Beverly Prods’ Sarah Timberman and Carl Beverly and Sony TV-based Judith Verno, as well as John Madden, who is set to direct. Under new Showtime president David Nevins, Showtime has had no problems landing features stars for its new series and pilots, including Claire Danes in Homeland, Don Cheadle in House Of Lies, and Liev Schreiber in the pilot Ray Donovan.