Sitting through “The Last Word” is like wandering around an artificial flower store. Every once in a while, you come across something quite lovely, and it grabs your interest for just a moment — but upon closer inspection, it’s phony and it’s plastic and it doesn’t pass the smell test.

Shirley MacLaine’s brassy, commanding performance notwithstanding, this is a manipulative, contrived and at times borderline offensive comedy/weeper with a number of cringe-inducing, off-putting elements.

Based on director Mark Pellington’s opening montage, featuring dozens of photos of MacLaine as a little girl, through early glamour shots, to pics of hitting the town and triumphantly holding up awards, through her golden years, one might think this is going to be a biopic about a movie star not unlike the real Shirley MacLaine.

No such luck. MacLaine’s character is Harriet Lauler, a retired advertising executive occupying a large and tastefully appointed but empty (save for the help) house, while living a small and quiet and empty life.

Harriet, we soon learn, deserves her solitude. She’s a hard and petty woman, a control freak who berates her gardener for not knowing the proper way to trim the hedges and elbows the cook out of the way in the kitchen. She’s been divorced for nearly two decades, she hasn’t talked to her daughter in five years, she had a bitter departure from the advertising firm, and she doesn’t have a friend in the world.

None of this seems to bother Harriet — until a number of her friends and colleagues pass away, and Harriet reads their glowing obituaries, and she realizes she needs to shape her legacy NOW, or her obit is going to be short and sour.

Let the plausibility-stretching contrivances begin!

Harriet marches into the newspaper her firm has essentially kept afloat for decades and tells the editor she’ll need the services of the obituary writer for the next few weeks so the writer will do justice to Harriet’s memory.

Right. Because that’s how it works.

Amanda Seyfried gives a sweet and earnest performance as the Anne the obituary writer, who is only about 30 but has already worked this beat for eight years. If you think we’re going to get some metaphors about how Anne herself needs to get out and LIVE instead of wasting her prime years writing about the deceased, ding-ding-ding-ding! Well played.

If the Harriet-Anne pairing wasn’t bad enough, theirs is the most natural of instant relationships compared to the introduction of Brenda (AnnJewel Lee Dixon), a young “at-risk” black girl. Harriet plucks Brenda out of a group of children at a community service and announces she’ll be mentoring Brenda, because it’ll look good in Harriet’s obituary.

When we meet Brenda, she has a foul mouth, a temper problem and an attitude. Within days, she’s holding hands with Harriet and Anne as they go on a road trip (another forced plot development), cracking cute one-liners and proclaiming, “Best day ever!” when the three of them have a sleepover in a crummy motel. (Because their car broke down. Because it needed to break down so we could have the sleepover scene.)

At times “The Last Word” veers from cloying to smug, e.g., the scenes involving a hipster radio station where various clichéd characters spin only the coolest music on vinyl. Thomas Sadoski plays a DJ/program director who’s so achingly mellow and laidback and comfortable with his coolness, even he acknowledges, “That sounded kind of douche-y,” after a particularly egocentric monologue about himself.

At 82, Shirley MacLaine is still a big-screen force. With a quick dismissive glance or a sharp-edged delivery of a one-liner, she creates a handful of genuine and genuinely funny moments. The scenes between MacLaine and Seyfried — just the two of them — are the best in the movie. With each introduction of an estranged family member or a former business partner or that annoying radio host, “The Last Word” becomes ever more crowded and ever less interesting.

★1⁄2

Bleecker Street Media presents a film directed by Mark Pellington and written by Stuart Ross Fink. Rated R (for language). Running time: 108 minutes. Opens Friday at local theaters.