“Moving On” is an amusingly edgy geriatric comedy that provides that late career comic duo Jane Fonda and Lily Tomlin with their best star vehicle since “Nine to Five.”

The laughs are droll, and unlike the strained “Grace & Frankie” and lumbering “80 for Brady,” the effort doesn’t show. They’re just two graceful pros, effortlessly playing to their strengths and put through their paces by a writer director (Paul Weitz), who gives them a vehicle worthy of their reputations and talent.

Claire (Fonda) is an 80ish Ohioan who leaves behind her beloved corgi (Dashiell), less-beloved daughter and grandkids to travel to a California funeral. One of her best friends from college has died.

She waits for her moment before the service to pass her condolences on to Joyce’s widowed husband, Howard (Malcolm McDowell). She looks him square in the eye, not a trace of pity in her.

“I’m going to kill you,” she says. “Now that she’s gone, now that it won’t hurt her…this weekend” will be his last, she vows.

Howard is a little rattled, but plainly he knows something we don’t. He has no trouble collecting himself for the eulogy he begins to deliver.

That’s when blowsy, out-of-effs-to-give Evelyn (Tomlin) strolls in and interrupts. She was Joyce’s college roommate, a concert cellist, a bit of a loner, and not all that interested in reconnecting with Claire after the service. A lift? No thanks, I ‘ll take the bus.

“I’m gonna KILL the bastard” leaves Evelyn unmoved. “I’m gonna buy a gun and I’m gonna take it to the wake!”

“Sure, Scarface. Sounds like fun.”

The dynamic is established. Evelyn knew Claire way back. She’s all talk and no follow-through. And Claire? She’s so out of touch with Evelyn she has no notion of her life since college, or that she’ll actually help her accomplish for this rash, violent act.

It’s a tribute to these two, wholly comfortable with each other’s timing and rhythms, that they make this nasty proposition funny — the committed but unreliable killer, the cynical, snarky, half-disinterested “old friend.”

And it’s a tribute to Weitz (“Grandma,” “About a Boy,””Admission,” “Little Fockers”) that this perfectly cast script keeps its secrets, keeps things moving along and keeps us interested with every new revelation and character addition along the way.

McDowell makes a grand straight-man in all of this, a widower with a point of view whose mourning and tolerance of Claire could very well be masking something else. That’s a nicely-turned-out character arc, and well-played.

Richard Roundtree is at his most courtly and chivalrous as one of Claire’s exes. And young Marcel Nahapetian makes a mark as the grandson of one of Evelyn’s neighbors in assisted living, a neglected kid whom she sees even if his parents and grandfather do not.

“My grandson?”

“Well maybe. Time will tell. But let’s not get into that.”

Yes, a lot of the laughs are of the low-hanging fruit variety. But they’re on a higher plane than anything in the cumbersome “80 for Brady.” Two “love birds” are “love pterodactyls” at “our age” is par for the course.

“Moving On” is still more than funny enough to coast by, but demanding in ways that flatter and honor its seasoned cast, each of whom gets the best role she or he has had in years thanks to Weitz’s light comedy with a dark edge.

That one time I interviewed Jane Fonda? Right here.

Rating: R, for violence and profanity

Cast: Jane Fonda, Lily Tomlin, Malcolm McDowell and Richard Roundtree

Credits: Scripted and directed by Paul Weitz. A Roadside Attractions release.

Running time: 1:25