Is there a director working today who’s a greater shape-shifter than Lasse Hallström? When you buy a ticket to a movie made by, say, Quentin Tarantino, Tyler Perry, Wes Anderson or Michael Bay, you know what to expect — for better or worse. The accomplished Swedish filmmaker, on the other hand, can’t really be said to have a signature style. He just has style.

He’s brought that style to projects as diverse in theme, look and tone as What’s Eating Gilbert Grape, The Cider House Rules, Casanova, The Hoax and Chocolat. It saturates every frame of Salmon Fishing in the Yemen, a picture in perhaps the most improbable of genres — the Middle East-based romantic comedy. That’s right: Hallström has managed to make a feel-good movie with terrorists.

The idea is that there’s this billionaire sheikh who’s crazy about fly-fishing, played by the charismatic Egyptian actor Amr Waked. In his travels, the sheikh has fallen in love with the sport and sees no reason why citizens of his war-torn country shouldn’t have an opportunity to get in on the fun.

Ewan McGregor sees plenty of reasons. He stars as a tweedy fisheries expert named Alfred Jones. Emily Blunt is Harriet Chetwode-Talbot, the sheikh’s London rep. When she attempts to enlist Alfred’s help in bringing fly-fishing to the desert, she’s met not just with resistance but with outright mockery. It’s the desert. Duh.

One of the clever things Hallström and screenwriter Simon Beaufoy (Slumdog Millionaire) do here is chip away, fact by surprising fact, at McGregor’s — and the viewer’s — assumptions. The Yemeni climate turns out to be more accommodating than the scientist realized, comparable to parts of California where salmon thrive. We learn that work has already begun on a cutting-edge dam capable of transforming a river in the middle of a wasteland into a series of waterways simulating the species’ natural habitat. Given that money is no object, McGregor’s character comes to embrace the quixotic project as a not-so-impossible dream. All they need is 10,000 fish and a way to get them from England to the Arabian peninsula.

That’s where the British government comes in. The script is adapted from Paul Torday’s 2007 novel of the same name, a political satire that was a hit in the UK. When a British-led operation in Afghanistan goes terribly wrong and threatens to become a PR nightmare (can you say “ripped from the headlines”?), the prime minister’s press secretary makes it her mission to divert the world’s attention with a heartwarming headline. Kristin Scott Thomas plays the hard-charging Patricia Maxwell, who gets wind of the salmon plan and seizes on it as a symbol of improved Anglo-Arab relations. Because she wants her photo op, she wants the sheikh to get his fish.

But will the boy get the girl? And, more importantly, will we care? McGregor and Blunt are winning as the mismatched pair with more than a few obstacles between them and true love. He’s in a rut of a marriage, and she’s dating a soldier who’s MIA. Such things have been known to work themselves out in 111 minutes, however. And, of course, further questions remain: Will the salmon adapt to their new home or wind up dead in the water? Will mistrustful insurgents get to the sheikh before he can realize his vision?

Fortunately for anybody eager for a big-screen break from vampires, superheroes and anything involving found footage, Hallström has realized his. Which, in this case, was to make a movie like they used to. This is an endearingly old-school exercise refreshingly devoid of angst or irony. The mood is a playful combination of the comic and the whimsical, the camerawork is spectacular, the dialogue is effortlessly fine, and there isn’t a performance that’s less than a pleasure to watch. The latest addition to one of the cinema’s most offbeat bodies of work is a fish-out-of-water story I strongly recommend you catch.