Fleeing the June 1940 arrival of Hitler's army in Paris, a pretty young war widow (Emanuelle Béart) and her two children are rescued from dive-bombing German fighters by a cocky, reckless teenager (Gaspard Ulliel) -- and his inbred instinct for survival quickly becomes the family's salvation in "Strayed," a drama of fugitive subsistence and uneasy camaraderie from French director André Téchiné ("Alice et Martin").

Much to the discomfort of Béart, who clings idealistically and insistently to the conventions of civilized society as the world falls apart around her, the courageous but disconcerting young man leads her family far off the beaten path, convinced that nowhere is safe to hide until they stumble upon a remote and abandoned chateau.

Over the course of several weeks as squatters (or maybe it's months -- the film's timeline is unclear), an uneasy new family unit forms as Béart's 13-year-old son (Grégoire Leprince-Ringuet) takes a brotherly shine to his emotionally unpredictable savior, whose elusive, paranoid behavior suggests he may be a deserter. But while the young man's looting of empty villages becomes their sustenance, his volatility and cache of weapons taken off dead soldiers keeps the mother on edge.

Beautiful, multifaceted Béart and furtive, cunning Ulliel (who looks like a skinny young Matt Damon) make this unsteady trust and unstable interpersonal dynamic the very essence of "Strayed," in which Téchiné navigates a minefield of expectations and seemingly contrived possible tragedies. The director never goes for the obvious, which is to the film's benefit -- most of the time. But at some point "Strayed" begins to derail.

It could be when the family's vigilance drops, leaving them vulnerable to being inadvertently discovered by local police -- or worse, by soldiers. It could be during a gratuitous, ill-fitting, highly unlikely sex scene. But the effect ripples through the rest of the picture, and causes the story to lose its bearings, leading to an ending that drops off a narrative cliff.