Two lovers named Bobby and Kate, played by the pretty but baffled-looking Joseph Gordon-Levitt and Lynn Collins, loiter on the Brooklyn Bridge on a hot July 4 to argue about whether there’s a baby in their future. They flip a coin, then blunder their way through two parallel fantasies exploring their dilemma. A wan domestic drama about the undercurrents of discontent and regret in Kate’s close Argentine family is intercut with an aimless action thriller involving the couple stumbling on a lost cell phone, countless conversations with “Dmitri,” a mystery-man with a dark-brown voice, and even more chase sequences running across Chinatown with an impassive Asian in hot pursuit. In principle, I like to see control freaks like David Siegel and Scott McGehee let down their hair. In practice, the talents of this long-time directing duo lend themselves far more to high-concept endeavors like the excellent The Deep End than to this heavily improvised waffle, shot with a handheld camera to underscore its open-endedness. The result is some nice atmospherics tethered to a cripplingly half-baked existentialism. “I guess we just keep going,” murmurs Kate—or is it Bobby?—toward the end. Uncertainty feels like what it is, an off-the-cuff diversion from a bigger project that wasn’t proceeding as planned.