For more than a decade Kevin Spacey has been trying to build a biopic around reptilian pop singer Bobby Darin (1936-'73), and his determination pays off in this glorious mess of a movie. The production numbers and nightclub showstoppers are impressive not only for Spacey's impersonation of Darin but for their skillful evocation of musical moments from the golden age of Hollywood, which are a world apart from postmodern exercises like Chicago and The Phantom of the Opera. Spacey also directed and cowrote the disjointed script, which adopts the self-referential mode of All That Jazz as it puzzles over Darin's confused parentage, loyal entourage, and marriage to Sandra Dee. This sags in the middle, and Spacey overlooks some of Darin's more interesting films (John Cassavetes's Too Late Blues, Hubert Cornfield's Pressure Point). But as long as Spacey is singing, the movie soars. With John Goodman, Bob Hoskins, Kate Bosworth, and Brenda Blethyn. PG-13, 121 min. Starts Wed 12/29: Lake, Landmark's Century Centre.