Colin Firth and Laura Linney to star in "The Joy of Sex" film about the notorious 1972 sex guide

Director Sharon Maguire ("Bridget Jones's Diary") has assembled the cast for her new comedy "The Joy of Sex," dramatising the true story behind Alex Comfort's notorious 1972 sex guide, which sold over 15 million copies worldwide and topped the New York Times bestseller list for 70 weeks. Colin Firth plays author Alex Comfort, Laura Linney plays his wife Ruth, and filming has just begun.