New York City has become so safe that Woody Allen was forced to relocate to London to become a killer. The bard of Manhattan is now on his third U.K. murder mystery, and this one is all British: Scarlett Johannson is nowhere to be seen, and Allen himself stays off camera. These are auspicious omens, but avoiding bad performances and stale jokes isn’t enough to make a good film. In fact, the lack of an American-abroad perspective hurts the movie, since the writer-director’s British characters and milieu are never entirely convincing.

In Match Point and Scoop, Johannson played a young Yank whose beauty provided her a pass into the local aristocracy. Most of the people she met seemed to have walked out of an Edwardian novel, but at least their detachment from commonplace travails located them in a similar realm to Allen’s customary demimonde, the Upper East Side. For Cassandra’s Dream, the filmmaker goes downscale, so he’s attempting to portray both a country and a class he doesn’t really know.

Short on laughs yet not precisely a drama, the story centers on two brothers who can’t finance their dreams on everyday wages. The more impulsive Terry Blaine (Colin Farrell) is content to work as an auto mechanic, but he’s also a gambler who immediately spends any winnings. Cassandra’s Dream is named for the boat he buys, at the film’s opening, with dog-track winnings. Later, Terry gets into high-stakes poker, and into debt to buy the apartment coveted by loyal girlfriend Kate (Sally Hawkins). When he loses almost $200,000, Terry turns to brother Ian (Ewan McGregor), who works at their father’s restaurant. By nature more calculating and circumspect, Ian also needs a few hundred thousand, or more. He’s romancing attractive, ambitious stage actress Angela (Hayley Atwell), and impresses her by posing as a wealthy hotel investor who can take her to Hollywood.

Economic salvation and potential damnation arrive in the same person, the brothers’ Uncle Howard (Tom Wilkinson), a plastic surgeon who got rich in image-crazed California. Howard is not about to give the boys a loan, but he wants to hire them for a small job: “getting rid” of one Martin Burns (Phil Davis), a colleague who’s about to testify against Howard in some (unexplained) investigation. The brothers are shocked, but Ian quickly accepts. Terry is hesitant, which establishes the dynamic for the rest of the movie.

The detective story is an inherently conservative genre, and a refuge for older writers – William Faulkner, notably – who’ve lost their inspiration. It’s also a form that can be repeated over and over, with small variations, which suits Allen’s longstanding determination to make movies quickly, cheaply, and regularly. Add Britain’s generous financing of film production and Allen’s appeal to skilled actors, and the result could well be a recipe for the rest of the director’s career. Cassandra’s Dream shows precisely how well the formula works: The movie has no emotional resonance, and little sense of place, but it’s watchable, thanks especially to Farrell, Wilkinson, and such supporting players as David Horovitch and Cate Fowler (who play Terry and Ian’s parents). Less credit goes to Philip Glass’ retread score and Vilmos Zsigmond’s mundane cinematography.

CASSANDRA’S DREAM ( 2 ) Directed by Woody Allen. • Starring Colin Farrell, Ewan McGregor and Tom Wilkinson. • PG-13, 108 min. • At the Osio Cinemas.