The Berlin film festival gets off to the ropiest start with this inert, implausible, often bafflingly acted ensemble movie from Lone Scherfig about lonely souls who miraculously find each other in New York. It’s what might be heart-sinkingly called a modern-day fairytale – but the kind of modern-day fairytale that gets both halves of the equation wrong, giving you something twee and improbable, weighted down by a dreary yet unconvincing realism.

There are some decent moments: Bill Nighy is often amusingly eccentric as Timofey, the Russian-American proprietor of a failing Manhattan restaurant, and he does have one very funny line as he serves some dishes to two diners and then, having turned to leave, wrongly assumes one of their intimately intense questions is addressed to him. And Zoe Kazan certainly pulls out all the emotional stops playing Clara, on the run with her two boys from a terrifyingly abusive cop husband.

But the performance of Tahar Rahim, as Timofey’s restaurant manager, really is not one for the showreel. It’s one that he may now wish to have scrubbed from his IMDb credits. This is not his first English-language performance. But his line readings are mysterious. The American-accented English is challenging. He gives every appearance of not understanding a single word that comes out of his mouth. But then the direction is uneven generally, and the film itself sometimes appears to have been Google-translated from Danish via Welsh. Scherfig herself has directed some great English-language pictures, such as An Education and Their Finest, but the screenplay she has written here is uncertain.

Rahim’s character is called Marc, an ex-con now going straight and his best friend is John Peter (played by Jay Baruchel), the lawyer who took his case. John Peter accompanies Marc to the forgiveness group therapy session at a local church, being run by ER nurse Alice (Andrea Riseborough), who does this in her spare time out of the goodness of her heart, though she is secretly hardly less unhappy than the regular attendees. Poor Clara is to come into contact with all these people as she flees her family home in Buffalo, New York and takes the kids to Manhattan, where she hopes her violent husband can’t find them. They sleep in her car at night and during the day, while the kids are dozing in the public library, she forages by shoplifting and stealing leftover food on trays in hotel corridors. The film shows a civil court proceeding for child custody and then a criminal trial for assault lasting a painless month or so, passing in a very brisk montage.

Meanwhile, the strangest and most jarringly unsuccessful character is Jeff (Caleb Landry Jones), an incorrigible guy who reacts to being fired from a mattress shop by throwing a swivel chair through a first-floor window. Is he supposed to have a creepy violent temper, like Clara’s husband? Evidently not. But if he’s supposed to be a sympathetic free spirit, then I guess it’s pedantic and beside the point to care about who that chair might have landed on.

The Kindness of Strangers is one of those terrible ideas for a film: ensemble dramas that are superficially attractive because of all the big names shoehorned into the cast-list. It’s a bit like Fernando Meirelles’s awful film 360, which brings together a similar bunch of uninteresting characters made even more uninteresting by the tiresomely unreal way they are corralled together. And the film is furthermore naive about showing homelessness as a problem to be cured with romance. Still, Nighy has some fun with his wacky cod-Russian accent, arguing with his partners: “Please, Sergei! We’ve had this conversation!”