Toronto International Film Festival

TORONTO -- A found cell phone and a lost dog figure into the parallel scenarios set off by the flip of a coin in "Uncertainty," an intriguingly constructed "what if" drama from the filmmaking team responsible for "The Deep End."

Feeding off of the incomparable energy of New York City as well as capable leads Joseph Gordon-Levitt and Lynn Collins, the new Scott McGehee and David Siegel collaboration starts off with a bang but unfortunately loses momentum as it goes along.

The end result makes for ideal festival fare, but its theatrical prospects-it went in to Toronto still seeking a distributor-seem less assured.

Both stories have their jump-off point at the same juncture of the Brooklyn Bridge on a bright, Fourth of July morning.

Upon flipping a quarter, Gordon-Levitt's Bobby and Collins' Kate take off in dramatically different directions-one leading to Manhattan, the other to Brooklyn.

While their Manhattan adventure starts off with a cell phone discovered in the backseat of a cab, leading to a murder, gunfire and rooftop pursuits, the parallel Brooklyn story focuses on family and unrealized hopes and dreams.

At first glance the dual stories couldn't appear to be more different, but they both share that element of uncertainty.

They do represent two sides of the same coin, after all.

But while McGehee and Siegel elicit believable, loosely improvisational performances out of Gordon-Levitt and Collins, after a strong start, those alternate realities prove less compelling as they unfold.

In a way, the film ultimately gets snagged in its own contraption.

Until that point, "Uncertainty" possesses a nice, kinetic vigor thanks to the handheld, HD camerawork of Chris Doyle protegee Rain Li, and Paul Zucker's fluid editing, which shifts back and forth surprisingly smoothly considering the distinctly different tones.

Production company: kinoCorp
Cast: Joseph Gordon-Levitt, Lynn Collins
Directors: David Siegel & Scott McGehee
Screenwriters: David Siegel & Scott McGehee
Producers: David Siegel & Scott McGehee
Director of photography: Rain Li
Production designer: Debbie De Villa
Music: Peter Nashel
Costume designer: Stacey Battat
Editor: Paul Zucker
Sales Agent: Cinetic Media
Not yet rated, 101 minutes.