Joel and Ethan Coen's new film "Inside Llewyn Davis" works so well in large part because of the remarkable performances. As the title folk singer, Oscar Isaac perfectly balances comic and serious aspects of the character. And as Jean, who may be pregnant with Llewyn's child, Carey Mulligan captures a mix of frustration and exhausted love that makes their scenes together deeply moving. Katherine Tulich had a chance to talk to them about working with the Coens to capture the early '60s folk moment.