Pierce Brosnan, Helena Bonham Carter and Gabriel Byrne appear on screen together for the first time in “Four Letters of Love,” a lovely, sentimental and ever-so-Irish romance about fate, faith and the power of words to woo, especially when folded into those old fashioned envelopes we used to drop in the post.

It’s a ’70s period piece directed by Polly Steele (“Let Me Go”) and adapted by Niall Williams from his own novel about a couple “meant” to be together who take an entire film — with tragedies, missteps and missed connections — to find their way to one another.

From “Much Ado about Nothing” to “Serendipity” and “Four Weddings and a Funeral,” that’s been a formula that works. On some of us, anyway.

Young Nicholas (Fionn O’Shea of TV’s “House of Guniness”) narrates our story, about the day “God spoke to (his father) for the first time” and upended his and his mother’s lives. Dad (Brosnan) was a civil servant, toiling away at his Dublin job-for-life until the moment the sunlight hits his desk blotter in a way that tells him he was meant to paint.

William Coughlan abruptly walks out on the job, shocks his wife (Imelda May) and leaves his son confused and bereft. Dad may wander off to “the mythic West of Ireland” to paint impressionist seascapes of this one island he’s fixated upon. Nicholas loses his father and watches his mother come to pieces over this disaster.

Meanwhile, young Isabel or “Izzy” (Ann Skelly of Netflix’s “The Sandman”) is coming of age on that island when her Gaelic-speaking family is visited by a different tragedy. Her older brother Sean (Dó`nal Finn) has a stroke while playing a pipe for her to dance for by the sea. Her published poet father (Byrne) falls into writer’s block, and his wife and muse (Bonham Carter) is bereft.

There’s nothing for it but for Izzy to attend a distant Catholic girls’ school to get her away from their grief.

Nicholas, “a son who could not speak to his father,” must find and make a connection with a man who thinks “All this time I’ve been living the wrong life.” And the girl with the father who shouts at God over his stricken son’s fate will find her escape from the nuns in the form of a rakish slightly older mamma’s boy (Ferdia Walsh-Peelo) with a steady job, a roaming eye and a Triumph 2000 to whisk her away from her troubles.

The obstacles to love in this romance are both practical and ethereal. How does a broken-hearted son cope with a father who takes a bit of sunlight through a skylight as a “sign” from above? At least the distance between our two prospective lovers — the island is only reachable by ferry — offers some of the most beautiful scenery on Earth. The County Donegal in Ireland and Ulster and Murlough Bay in Northern Ireland settings will have romantics plotting their next cliffside vacation.

A longer cut of “Four Letters of Love” — the title’s a pun on the spelling of “l-o-v-e” — played festivals and was released in theaters. But losing 16 minutes before its streaming release was almost certainly for the best. Novelists who adapt their own books into scripts tend to avoid murdering “their darlings” and this lumbers during the early acts and the almost omnipresent novelistic voice-over narration grates — it’s an unnecessary crutch in most movies — until it finally pays off.

But Brosnan grows his hair out and shows off his painterly eye (he really paints). Byrne has spent most of his wide-range-of-roles career hinting at the fact that he was born to play an Irish poet.

And Bonham Carter lands all the laughs as she twinkles and casts side-eyes in the film’s utterly delightful and wholly charming third act, when her character’s morality demands that she try to keep Nicholas’s heartfelt written odes from reaching the fair Izzy.

Spoiler alert — her efforts come to naught. And this engaging make-work project for cherished older actors touches as they sparkle and remind us all, and the younger characters around them, that they know what it’s like to be young and in love and remember the blush of recieving the perfect love letter.

Rating: PG-13, adult themes

Cast: Pierce Brosnan, Helena Bonham Carter, Fionn O’Shea, Ann Skelly, Ferdia Walsh-Peelo, Dó`nal Finn and Gabriel Byrne.

Credits: Directed by Polly Steele, scripted Niall Williams. A Quiver release on Amazon Prime.

Running time: 1:49