'Quantum of Solace' star Daniel Craig makes a serious departure from his 007 persona in the extraordinary, true-life war tale, 'Defiance.' Craig and the film's big stars dish with ET's Mary Hart about what it was like making the movie, and they talk about how they kept things light on the set.

Daniel stars opposite Liev Schreiber and Jamie Bell as Eastern European Jewish brothers in 1941 who band together for survival -- and end up avenging the deaths of their loved ones while saving countless others during World War II.

"What inspired me most about this story is that there is hope," Craig tells ET about keeping things light on the set of the dark film. "...I imagine that is how people sort of kept their spirits up -- they joked and they laughed and they made sort of fun of the situation in spite of how awful it was."

In select theaters Dec. 31 and in wide release January 16, 'Defiance' is based on the book Defiance: The Bielski Partisans by Nechama Tec, and directed by Ed Zwick ('Blood Diamond,' 'The Last Samurai,' 'Glory').