The heat of unexpected passion scorches two lost souls in Jason Reitman's handsome adaptation of the novel by Joyce Maynard.

Embellished with a present-day voiceover that harks back to events of one sweltering summer in 1987, Labor Day woos us with stirring performances, Eric Steelberg's sun-dappled cinematography and Rolfe Kent's elegiac orchestral score.

Scenes between Kate Winslet and Josh Brolin as the doomed lovers simmer with eroticism, including a glorious set-piece with a homemade peach pie that makes our pulses quicken and mouths water.

Fifteen-year-old rising star Gattlin Griffith is equally compelling as the painfully shy teenage son, who witnesses this mending of broken hearts in impossible circumstances.

Yet for all of its impressive qualities - and they are bountiful - Labor Day isn't quite the sum of its parts.

The condensed timeframe of the central romance strains credibility and some of the subplots feel undernourished. Reitman's mosaic of flashbacks and reminiscence creates a fractured chronology that hampers dramatic momentum, dissipating the sense of dread and longing that should permeate every impeccably crafted frame.

"It was just the two of us after my father left," explains 13-year-old Henry Wheeler (Griffith).

So the youngster nervously takes on the mantle of man of the house, tending to his depressed mother Adele (Winslet). Once a month, they venture out for supplies but for the most part, Adele remains indoors, haunted by ghosts of her failed marriage.

During a visit to the local Pricemart with his mother, Henry encounters a bloodied stranger called Frank Chambers (Brolin).

Under duress, Adele and her son take Frank into their home and tend to his wounds.

That night, a television news report reveals the intimidating man is an escaped prisoner serving 18 years for the murder of his girlfriend (Maika Monroe).

"It didn't happen that way," growls Frank.

The fugitive lays low at the Wheeler homestead and adopts the role of surrogate father, teaching Henry how to pitch a baseball and lavishing Adele with tenderness.

"I could feel her loneliness and longing before I had a name for it," notes Henry as he becomes a silent observer to the strengthening of bonds between Frank and his mother into a second chance at happiness.

Labor Day hinges on the screen chemistry between Winslet and Brolin and we believe in their emotional connection, although the film skirts perilously close to melodrama when Frank tells Adele, "I'd take 20 more years [in jail] just to spend another three days with you."

Griffith is mesmerising in a demanding role and he wrings out tears beautifully and convincingly at a critical juncture.

A coda, set in the present day, feels cheap and unnecessary.

The heart wants what it wants and according to Reitman, our hearts want to feel warm as we leave the cinema.