Suspenders of Disbelief: Hanks? Wilson gets a crash course in Cold War geopolitics.

Julie Christie gave one of the year’s most graceful film performances in Away From Her, playing a woman quietly surrendering to Alzheimer’s disease at a comfortable nursing home in a bucolic setting. The vision of degeneration in The Savages is nothing like that. In the first scene of writer-director Tamara Jenkins’ bleakly hilarious family satire, Lenny Savage (Philip Bosco) is fighting about his excrement with a health-care aide in Sun City. And the Arizona senior mecca is just the foyer to the abyss: Buffalo. That’s where Lenny, who’s showing symptoms of Parkinson’s disease, is sent after he’s evicted by the children of his elderly paramour after she drops dead at a nail salon.

Lenny is not alone in the world, but his children wish he were. Jon (Philip Seymour Hoffman) and Wendy (Laura Linney) haven’t been close to their dad, and the effect of that strained relationship is reflected in their distance from everyone else. Jon, a college professor specializing in Brecht, won’t marry his girlfriend, even though his refusal means she’ll have to return to Krakow. Wendy, a self-styled “subversive” playwright who pays the rent as an office temp, is conducting a weary affair with a married neighbor, despite having promised everyone—­including herself—that she’ll end it. Now these overgrown adolescents will have to be adults, even though Jon is a petulant small-time bully in a neck brace and Wendy is a chronic fibber with permed ringlets that went out of fashion when she was in junior-high.

“We are horrible people,” Wendy exclaims after she and Jon check their father into a “rehabilitation center” that can’t and won’t rehabilitate him. They aren’t, of course. They’re normal people, which is to say they’re distracted, bewildered, and sometimes self-serving. A believer in self-improvement and pills, Wendy gives her father a small statue of Ganesha, the elephant-headed Hindu remover of obstacles, and ginkgo biloba “to boost brain function.” (She, meanwhile, pops Percocets filched from Dad’s late girlfriend.) Movie night at the nursing home proves awkward when Lenny chooses The Jazz Singer, a film that reminds him of his Jewish Lower East Side childhood but offends the African-American staffers. Death is inevitable, but The Savages remembers that it’s a comedy and ends with a set of modest but touching second chances: one offered to Jon, the other offered by Wendy.

The soundtracks of The Savages and Juno, another recent film that mines humor in grim themes, overlap in places, most curiously in their mutual inclusion of “I’m Sticking With You,” a Velvet Underground oddity. Yet Jenkins’ masterly film is not just another indie trifle that masks cheap sentiment with hip quips. Beautifully performed and emotionally resonant, the movie uses laughs to reveal depths of character, not to camouflage shallowness. Its humor, never facile, thoroughly interweaves other feelings, including dismay, confusion, and relief.

When Jon gets to see Wendy’s new play, she keeps asking if it’s self-involved. It is, and so is The Savages, but that’s not a complaint. Like Jenkins’ only other feature, 1998’s Slums of Beverly Hills, this movie springs from the director’s own life. Yet that inspiration has yielded not narcissism but people who are believably specific, thrust into a situation that’s nearly universal (or will be soon enough). Jenkins is too smart, witty, and skeptical to spin Lenny’s decline into a typical disease drama; she instead straddles the boundary between tragedy and farce, never losing her balance or compassion. When she decided to give her characters the surname “Savage,” it was just her way of saying they’re human.