You don’t think much about “character arc” in a movie until you stumble across a movie that forgets to tidy that detail up.

In “Fisherman’s Friends,” the reliable character actor Daniel Mays plays Londoner and musical talent manager Danny, the man who discovers Cornwall fishermen who’ve kept sea chanteys alive, as their ancestors did, for centuries. Danny turns them into pop stars in this “true story” about a British singing phenomenon of about ten years ago.

This sort of thing happens all the time in the UK, land of “The X-Factor,” Susan Boyle and — when I was a kid in the ’70s — Laurel & Hardy singing their way onto the pop charts, decades after their deaths, with the novelty tune “Trail of the Lonesome Pine.”

Either the real manager “Danny” got to the screenwriters, to Daniel Mays or his lawyers did. Because the edge is utterly rubbed off him. The classic way of portraying this guy is cynical, self-dealing city slicker who is moved, reformed and maybe butched-up by his dealings with working men of the sea. And there’s nothing of that to him, no edge, no real “journey” from A to B for this character to take.

Danny is pranked by his douche of a boss (Noel Clarke) on a group bachelor party/scouting trip to Port Isaac on the Cornwall coast, left behind by that boss to “sign,” “do what you do” with these ten local fishermen who sing “Nelson’s Blood,” “Blow the Man Down” and “What d’ye Do With a Drunken Sailor” on the docks every weekend they aren’t at sea.

To crusty Jim (James Purefoy, terrific), his crustier Dad Jago (veteran character actor David Hayman) and “the lads,” this Danny fellow is “just some wanker from London.”

But Danny, on the fly, starts in on “tradition” and “authenticity” and works his wordy charm, and they fall under his spell. It’s just that his boss, who ditched Danny there with lousy cell service and no transport to the big city “until they sign on the dotted line,” was just pranking him. His big talk of singers who “look the part” and songs “in the public domain” was just that. Danny?

“I gave them my word.”

So straight off, he’s a decent sort, an honorable man and somebody with no place in the cutthroat music business. If he can’t sneak out of town before making good, he’s in for a total immersion in generations of Port Isaac fishing culture.

“You’ll never know a man until you find out what his legs are made of…at SEA.”

And then there’s Jim’s single-mom daughter, the spunky Alwyn. As she’s played by Tuppence Middleton, Danny is of course smitten. And being a decent sort, from the start he’s chivalrous, charming her little girl if not her grumpy Dad.

When you label a tale like this “a true story” you’re kind of giving away the game. They don’t make movies about singers who don’t get a record deal and gain attention for it.

But even with much of the mystery missing, there are wrinkles in the tale, potholes — some tragic — on the path. As the fishermen also volunteer as the port’s rescue boat operators, there’s more than just fishing in the unforgiving sea that’s a risk.

As the poet Sir Walter Scott put it to any fishmarket shopper, “It’s no fish ye’re buying–it’s men’s lives.”

There’s also a sprinkling of “local color,” although not nearly as much as you’d hope from a movie that tells a 75 minute story in 112 minutes.

The coastal folk are “Yarney Goats,” and their nearby inland rivals are “Town Crows.”

Danny has to go to sea, but not “dressed for an America’s Cup.” And dammit man, mind what colors ye wear aboard our boats.

“Fishermen don’t wear green. Makes the boat seek land!”

The scenery is lovely, the pub life palpably real and the songs, depending on your taste and “saltiness,” are lovely, rich and occasionally hilarious.

Note for North American viewers, there’s a joke about “The National Anthem” that you only get if you realize Cornwall was never formally bound in treaty to England and Britain. Kind of like Key West.

The movie this most closely resembles is the similar “true story” “Calendar Girls,” only with no nudity and less comic edge.

Still, Middleton, Purefoy, Hayman and Mays are interesting enough on their own that they make this mixed-bag of a movie tolerable even when it tests your patience, even when the characters don’t really take a personal journey that anyone could call “a character arc.”

MPA Rating: Rated PG-13 for some strong language, and suggestive references

Cast: Daniel Mays, Tuppence Middleton, James Purefoy, David Hayman, Maggie Steed and Noel Clarke.

Credits: Directed by Chris Foggin, script by Piers Ashworth, Meg Leonard and Nick Moorcraft. A Samuel Goldwyn release on Netflix.

Running time: 1:52