The new movie by Joel and Ethan Coen, O Brother, Where Art Thou? is a picaresque comic strip "based"--as the credits inform us with the filmmakers' trademark brand of knowing tongue-in-cheekiness--"upon The Odyssey by Homer." Set in the Deep South during the Depression, the movie does borrow certain figures from the ancient Greek epic (several sirens, the Cyclops, Penelope), but in relating the adventures of its trio of bumbling heroes, escaped convicts from a chain gang, the Coens also invoke other, less-than-classical sources, including The Beverly Hillbillies, Bonnie and Clyde, and, at times, Mad magazine.