Atwell's first major on-screen television role came in 2006 with BBC Two's miniseries, "The Line of Beauty". Later in the year, Atwell appeared as '415' in AMC Television's November 2009 miniseries, "The Prisoner", a remake of the 1967–68 series by the same name. In 2010 Atwell appeared in Channel 4's adaptation of William Boyd's, "Any Human Heart", and later that year, Ken Follett's miniseries, "Pillars of the Earth", which co-starred Eddie Redmayne; for which she was nominated for her first Golden Globe. In 2013, Atwell starred in BBC Two's adaptation of William Boyd's espionage novel, "Restless", before starring in "Be Right Back", an episode in Charlie Brooker's critically acclaimed science fiction television series, "Black Mirror". Atwell made the transition to film roles early on, with her first major role coming in Woody Allen's 2007 film "Cassandra's Dream", playing stage actress Angela Stark. In 2008, she appeared in the film "The Duchess," which earned her a Best Supporting Actress nomination at the British Independent Film Awards. Later that year, Atwell appeared in the Miramax film "Brideshead Revisited".