Starring Keira Knightley and Mark Ruffalo. Rated 14A.

The latest in a line of specialized movies aimed at smart people but widely missing the mark (hello, Chef and Words & Pictures), Begin Again should have started over with its boilerplate title. The original, Can a Song Save Your Life?, is more connected to a tale about a struggling U.K. songwriter named Greta (Keira Knightley) and a washed-up record exec called Dan (an amusingly scruffy Mark Ruffalo). But it also betrays the film’s surprisingly vague worldview.

Coming off the Oscar-winning musical Once, writer-director John Carney—a bassist in Glen Hansard’s Irish band the Frames—should have been able to mount a more ambitious musical. The first one worked so well with zero budget because: 1) Hansard and Markéta Irglová were enacting their own push-pull relationship; 2) the music was damn good; 3) all the tunes were rendered live wherever they happened (as with “Falling Slowly” in a Dublin piano shop).

In this slapdash Manhattan tale, the romance is tepid and the tunes, mostly written or cowritten by Gregg Alexander (formerly of the New Radicals), are only passable. That bit about raw recording is the real sticking point, especially because one of the thin plot’s few standout features is the decision by a fired-up Dan to record Greta’s CD in odd locations all over New York City. But whether performing at an open-mike coffeehouse, on a Financial District rooftop, on a subway platform, or beneath one of the city’s busy bridges, Knightley (who does her own singing, convincingly) comes out sounding exactly the same, with airless studio reverb and perfectly tuned instruments sealed tightly into place.

This sterile exercise has little room for character development, so we get montages and forced set pieces instead. Greta is getting over a bad breakup with her rock-star partner, played woodenly by Adam Levine, and hanging out with an expat busker (Brit comic James Corden). The Voice’s CeeLo Green shows up, as a rich rapper, to help booze-soaked Dan, who hasn’t had a hit in the post-biz period. After that, you keep expecting Christina Aguilera to swivel her chair around and punch a big red button. The only buttons punched in this poorly staged and shot effort, however, are the cheaply emotional sort, with Danny boy trying to reconnect with—what else?—his estranged wife (Catherine Keener) and resentful teenage daughter (True Grit’s Hailee Steinfeld). Maybe Once really was enough.