“And Mrs” is a bittersweet and offbeat romantic comedy of love and loss and mourning, and a most unexpected star vehicle for unfiltered Irish comic Aisling Bea, nicely paired up with Carrie Fisher’s kid, Billie Lourd.

Bea, one of the English speaking world’s greatest talk show guests, stars as a woman whose fiancé dies just before their wedding. Lost and bereft, she decides to follow through on “what Nathan wanted” more than anything else, to be married to her.

Gemma will battle friends, family, customs and her own guilty conscience to make this happen. And as she’s living in London, naturally there’s a loophole in arcane British law that allows such “necrogamy” nuptials.

Gemma, a London-Irish graphic designer, was never the “big gesture” and big emotions one in her relationship to Nathan, played by Colin Hanks. He botches his first “I Love You” by prematurely playing The Partridge Family’s “I Think I Love You” on his phone. He can’t get her to commit to an early “I love you,” just “I’m very, very fond of you.”

And he later made his very public proposal awkward enough for the record books.

But when she comes back from a morning run with her mates Ruth and Mo (Susan Wokoma and Omari Douglas) and Nathan doesn’t wake up, her shock is such than when the paramedics start zipping up the body bag, all she can think to say is “D’ye think he’ll be alright?”

Her parents (Sinéad Cusack and Peter Egan) are little comfort. Talking to Nathan, whom she still “sees” now and again, helps only so much. But when Nathan’s dizzy and somewhat less than considerate (never answers her phone or texts) sister Audrey shows up at the airport for the wedding, pink haired, gay and very pregnant from the surrogacy she took on to pay the bills, Gemma has an ally, someone “who gets me.”

Let friends and family tell her this idea of “doing what Nathan wanted” is “tasteless” and absurd, just a way of not coming to grips with grief. Short-skirted, impulsive and foul-mouthed mom-to-be Audrey is down for the dare.

“Grab hold of your labia! Let’s DO this!”

Melissa Bubnic’s script leans on the tropes of romantic comedies from “P.S. I Love You” to “My Best Friend’s Wedding,” with a particular focus on “Four Weddings and a Funeral.”

A clumsy hired officiant (Paul Kaye) begins the funeral with “It doesn’t matter if we’re one or 101, we’re never ready to say goodbye,” and then goes completely off the rails with tactless jokes and self-absorbed confessions that wholly misread the room.

Gemma’s mum and her bestie Ruth are dismayed at her fool’s errand of going through the motions — catering, bookings, fitting her dress and the like.

But brassy Audrey, given a kind of dazed disconnection in between outbursts of American self-righteousness by Lourd, becomes Gemma’s wounded ride-or-die, ginning up public outrage over a judge (Harriet Walter, droll) determined not to allow a loophole to puncture 200 years of precedent and tradition.

Yes, Gemma’s online and media nickname becomes “Corpse Bride.”

Director Daniel Reisinger has a lot of story, flashbacks and “explanations” to get through, so the film is longer than it feels. Nathan and Aubrey’s childhood must be contended with (Elizabeth McGovern is the estranged mom) and Gemma’s flashbacks underscore her own “issues.”

Lourd is game, if a tad underwhelming as the “nut” who gives the picture life, but better at hinting at the heart hurt Audrey is dealing with. Bea’s grim sarcasm nicely serves the character and the picture as she gets over her fury of having to break the news to Nathan’s “only family” that he’s died in the arrivals gate at Heathrow.

Of COURSE she’ll take Audrey in.

“Hardly going to throw a pregnant woman out in the streets. It’s not BETHELEHEM, after all.”

And Reisinger and Bubnic follow nuptial-comedy specialist P.J. Harvey’s (“Muriel’s Wedding,” “My Best Friend’s Wedding”) edict that when family and friends gather for weddings, they can’t resist a sing-along, the “comfort food” of any wedding comedy ever since Shakespeare’s “Hey nonny nonnies.”

The narrative has heart and hurt and laughs and a big finish. Sure, it’s formulaic and not every scene has a proper pay off.

But in a cinelandscape where rom-coms that work are as rare as hope for a better tomorrow, “And Mrs” plays, and gives Bea another year or two’s supply of chat show anecdotes and jokes. Not that she’s needed them.

Rating: unrated, with lots and lots of profanity

Cast: Aisling Bea, Billie Lourd, Colin Hanks, Susan Wokoma, Harriet Walter, Omari Douglas, Peter Egan and Sinéad Cusack.

Credits: Directed by Daniel Reisinger, scripted by
Melissa Bubnic A Vertical release on Amazon Prime, other streamers.

Running time: 1:51