Say this for Leonardo DiCaprio: He doesn't scare off easy from acting challenges. At 37, he's already played billionaire Howard Hughes (The Aviator), junkie Jim Carroll (The Basketball Diaries), great imposter Frank Abagnale Jr. (Catch Me If You Can) and Shakespeare's Romeo. In J. Edgar, DiCaprio ages from his twenties to his seventies to play America's feared and loathed top cop. And despite being buried in layers of (often too obvious) prosthetic latex, DiCaprio is a roaring wonder in the role. He needs to be. Until his death in 1972, J. Edgar Hoover ruled the Federal Bureau of Investigation like a bulldog no one would dare leash. That includes eight presidents, Martin Luther King Jr. and even Marilyn Monroe. For half a century Hoover nosed into private lives to control his enemies, and some friends. But Hoover had secrets too, and now acclaimed director Clint Eastwood, 81, and Oscar-winning Milk screenwriter Dustin Lance Black, 37, are doing the nosing around.

The result is a movie exhilarated by biting off more than it can chew, a great boon especially when the pacing goes from rushed to dramatically inert. The tabloid version of Hoover as a cross-dressing closet queen is addressed, but not exploited. Black's script isn't linear; it jumps back and forth in time with impressionistic glee, hoping to get a fix on an unknowable public figure.

The film focuses on those closest to J. Edgar: his autocratic mother, Annie Hoover (a splendid Judi Dench); his protective secretary, Helen Gandy (a sutured Naomi Watts); and FBI associate director Clyde Tolson (a live-wire Armie Hammer), the lawyer who became J. Edgar's constant companion.

Of course, Hoover's greatest obsession was America and his need to protect it from commies and radicals. In dark and weighted images, Eastwood charts Hoover's rise and all-consuming myth-building. Though Hoover did popularize fingerprinting and the collection of forensic evidence (the CSI TV franchise is in his debt), he liked giving himself credit where it wasn't due, for killing gangster John Dillinger, solving the kidnapping of Charles Lindbergh's baby, and being the ultimate G-man, making arrests and capturing bad guys. Eastwood busts that myth with the same fury with which he undercut the codes of the Old West in Unforgiven.

To its credit, Black's admittedly speculative script keeps nudging into J. Edgar's secret heart. Did sublimated sexuality drive Hoover into megalomania? Annie registers what's going on between her son and Clyde. In a wrenching scene, she derides any hint of effeminate behavior ("I'd rather have a dead son than a daffodil"). And DiCaprio and Hammer do wonders with mere suggestion, that is, when melodrama and old-age makeup allow for nuance. Even when the film trips on its tall ambitions, you can't shake it off.

Related
• At the Movies with Peter Travers: Leonardo DiCaprio Turns in a Great Performance in 'J. Edgar'
• Photos: Leonardo DiCaprio and More Leading Men on the Cover of Rolling Stone
• Leonardo DiCaprio's Life in Photos

“IRM”

Fashioned to mimic the sound of a magnetic resonance imaging or MRI, "IRM" (the French designation for the brain scan) grew out of Gainsbourg’s love of the sound of the clickety-clack of medical machinery. The IRM album project also marked the fulfillment of two goals for the singer: to document a traumatic experience, and to record an album with Beck. Though her co-creator and producer didn’t necessarily know the details of her water-skiing accident and resulting cerebral hemorrhage (which lead to the IRM of the song's title), he somehow knew how to handle the material. "Beck had a way of guessing what I was thinking and feeling without me telling him," said Gainsbourg. "We never discussed these things explicitly."