A pleasant fantasy with a crackerjack title, “Salmon Fishing in the Yemen” is a charming film whose few attempts at seriousness are best forgotten or ignored. When Emily Blunt and Ewan McGregor are your stars, that is easy to do. They bring to life the film’s very contrived plot about bringing British angling to the desert of the Middle East.

The film’s wayward stabs at significance are the vestiges of the well-received, bittersweet Paul Torday novel that started the ball rolling. But once-veteran crowd-pleasers, including director Lasse Hallstrom (“Chocolat,” “My Life as a Dog”) and screenwriter Simon Beaufoy (“Slumdog Millionaire”) became involved, the whole picture changed.

Among the more welcome alterations was to change the sex of a key character, a British government press officer, from a man to a woman named Patricia Maxwell. This allowed Kristin Scott Thomas to do a sparkling, take-no-prisoners comic turn as a sarcastic spin doctor who oozes fake charm, gets away with calling people things like “Sunny Jim” and does a riff on dialogue from HBO’s “The Wire” that is priceless.

She zestily gets the plot into gear when, faced with yet another in a series of colossal government blunders, she insists to her underlings that “we need a good news story in the Middle East, and we need it in an hour.” Enter salmon fishing and Yemen.

That counterintuitive notion was first floated, so to speak, by the bright and energetic Harriet Chetwode-Talbot (Blunt), a British investment consultant for “a client with very substantial funds” who is passionate about the idea of bringing salmon fishing to his native Yemen.

Harriet starts by trying to interest Alfred Jones (McGregor), one of Britain’s top fisheries experts, in the project. Crotchety, super serious and obsessed with his own work on fruit flies, the Scot couldn’t be less interested and treats the request like the ravings of a lunatic. “Fish require water,” he says carefully. “You are familiar with that concept?”

As it turns out, there are mountainous parts of Yemen that salmon might enjoy visiting, and with the government pressing him to cooperate in their public relations move, Alfred reluctantly admits that bringing the fish there would be theoretically possible if someone were willing to put 50 million pounds into the project.

Wouldn’t you know it, Harriet’s client just happens to be a billionaire sheik to whom tens of millions of pounds is pocket change. Charismatically played by Egyptian actor Amr Waked (“the George Clooney of the Middle East,” according to the film’s producer), the sheik is a man of faith who loves to fish and believes the activity can lift the spirits of his beleaguered people.

A man of great personal charm, capable of handling lines such as “I have too many wives not to know when a woman is unhappy,” the sheik takes Alfred fishing near a castle he happens to own in Scotland and makes a convincing speech about the wonders of fishing in general and the worth of salmon in Yemen in particular.

That, plus the political pressure of Patricia, who bites off dialogue like it was so much world-class toffee, makes a believer out of the scientist.