Seaside locations on the scenic Kentish coast, a period piece story set “during the war” and a stellar cast can’t quite make the debut feature of playwright-turned-writer/director Jessica Swale come off.

She’s probably kicking herself over “Summerland” as it is, what with wasting a rare pairing of Gemma Arterton and Gugu Mbatha-Raw. So I’ll leave my boots off for this review, no matter how disappointing the film.

It’s a sad, drab tale told by pretty faces in a pretty place, a slow-footed story wrapped in the most boring part of myths and legends — the academic study of them — and a love story tested by too-convenient coincidences.

We don’t have to ask who took lots of notes during “deus ex machina” week at playwrighting school, in other words.

An impatient older woman (Penelope Wilton of “Downton Abbey”) smokes and types away in 1975. Something gives her a case of the flashbacks, and she remembers a long ago summer in Kent, when she was even grumpier.

Alice Lamb (Arterton) is a loner who won’t let a little thing like World War II keep her from hunting for “the reality” behind famous bits of folklore and myth. She’s hated in the town, and her nicknames are many, which the headmaster at St. Nicholas School (Tom Courtenay) will list, when prompted.

“Bad apple,” “the beast on the beach,” “the witch,” “a Nazi” — that’s what the kids, and the adults, all say about her. Stomping about in trousers, chasing schoolboys who sabotage her mailbox and making littler kids cry are what “provoke” the locals. Not that she cares.

Then she’s abruptly “assigned” a little boy (Lucas Bond) who’s been evacuated from London, as children were in the early years of the war. All her outraged protesting gets her is a “We’ve all got to do our bit” lecture that lasts about as long as that sentence.

Her “find somebody else to take him” and “Don’t expect me to cook for you” barking isn’t what a lonely child needs to hear in a stranger’s home in a remote village. But she’s Miss “You’ve got to toughen up…Nobody likes a coward.”

But but “I always have milk before bedtime.”

“Good for you.”

Oh, she’ll soften. Maybe. A little bit. Eventually. His constant questions are the start of it, his thin grasp of her research — about King Arthur, Morgan Le Fay, “floating castles” (mirages) — makes her a teacher, whether she wants to be, or not.

“Summerland” is a piece of pagan myth that gives the film it’s title, and little else. Viking heaven? Kind of.

That’s kind of interesting but thinly developed. Even less screen time is devoted to his equally reluctant “partner” at school, Edie (Dixie Egerickx). She’s “an individualist” who doesn’t believe in “partners” or “sharing.” It’s all a pose. They become pals.

Alice spends part of each day rummaging through the kid’s things, picking up his story and reminiscing — yes, there are flashbacks within the flashback — to her long lost college friend (Mbatha-Raw) who was her one true love, back when both were flappers.

As her connection to Frank grows, she shares a little of that past with him.

Arterton does her utmost to make Alice funny-mean and lonely by choice. The script doesn’t give her many good moments, just a lovely deflated look when Alice gets the news that women often got “during the war” and most movies set “during the war” feel the need to replicate.

Mbatha-Raw has absolutely nothing to play, and whatever promise might have come from casting these two opposite each other is wiped away in flashbacks that serve a structural purpose, but fail to give them the emotional connection we need for us to feel the pain of their separation.

Courtenay and Wilton are similarly wasted, accomplished actors who sparkle when given a sliver of a chance, but so limited in screen time as to smother their contributions.

Even the kid with, his anachronistically long hair, fails to register.

Swale did some of her homework in setting her story mostly in 1942 or 1943. But no way this doctoral student of hers would have the petrol to galivant about looking for mirages when “there’s a war on.” Not that early in the war.

But it’s not period detail that lets “Summerland” down. It’s not moving beyond the story’s naturally watchable qualities (cast, setting, period) to give us a film that ever feels it doesn’t need one contrived situation after another just to stagger to its feet. Not that it ever moves those feet once it does, mind you.

MPAA Rating:  PG for thematic content, some suggestive comments, language, and smoking

Cast: Gemma Arterton, Gugu MBatha-Raw, Lucas Bond, Penelope Wilton and Tom Courtenay.

Written and directed by Jessica Swale. An IFC release.

Running time: 1:39