The buzz from smartass central is that Kevin Spacey, 45, will fall on his Oscar-winning butt as Bobby Darin, the brash, finger-snapping "Mack the Knife" singer whose heart condition killed him in 1973 at age thirty-seven. Spacey can now step up for the last laugh. A plot device that has Darin looking back on his life as a Bronx street kid, of records, nightclubs and films, and husband to troubled teen idol Sandra Dee (a sweetly affecting Kate Bosworth), allows Spacey to do the the role without a digital makeover.s director, Spacey can't stop the movie from groaning under the weight of biopic clichs. But the actor forges a bond with his subject that rights all wrongs. Doing his own singing (an uncanny imitation), Spacey is a marvel. He turns acting into riveting reincarnation and redoubles our appreciation of Darin, an underrated performer who used music to cheat death. Beyond the Sea, a tribute to both their talents, is one from the heart.