Henry (Gattlin Griffith), left, Frank (Josh Brolin) and Adele (Kate Winslet) grow close after an intense introduction in “Labor Day.” (Dale Robinette)

Labor Day” turns out to be aptly titled, and not only because it transpires over the course of one hot-and-heavy summer’s end in the mid-1980s. In this intense, exquisitely photographed domestic potboiler, both Kate Winslet and Josh Brolin deliver studiously serious performances, trying mightily not to betray how hard they’re working to overcome the preposterous story in which they find themselves.

Adapted by Jason Reitman from a novel by Joyce Maynard, this sexually charged wish- fulfillment fantasy — complete with troubling masochistic and Oedipal undertones — arrives with people already buzzing about its standout scene, in which Brolin’s charismatic ex-convict teaches Winslet’s depressive, agoraphobic housewife how to bake a peach pie (never before has the word “crumbing” been quite so erotically charged). But that turns out to be just one of the many gemutlich talents of Frank, who first meets Adele (Winslet) and her 13-year-old son, Henry (Gattlin Griffith), when they take a rare outing to buy school clothes.

Having recently escaped from prison, Frank forces himself into their car and proceeds to hold them hostage in their airless, unkempt house. Soon, the taciturn, rough-hewn dreamboat is changing the oil in Adele’s car, teaching Henry how to throw a baseball, waxing the floors and even ironing. It’s not for nothing that, back in the variety store, he emerged from behind a rack of superhero comics.

If only Reitman, best known for such comedies as “Juno,” “Up in the Air” and “Young Adult,” had brought some wit or swiftness to bear on Maynard’s painfully trite and retrograde plot, which grows only more contrived with the introduction of a creepily precocious girl whom Henry fatefully befriends at the local library. But “Labor Day” has been staged so handsomely, its actors delivering such alternately seductive and solemn performances, that the blame seems most fairly assigned to the source material, which resorts to facile captivity fantasies and cheap psychology, rather than the characters’ own contradictions, to make its dramatic points.

It’s difficult to believe a word of “Labor Day,” but then again you don’t have to in order to luxuriate in Winslet and Brolin’s bubbling, steaming chemistry. Still, between this, “Revolutionary Road” and “Mildred Pierce,” it seems past time for Winslet to cast off the sackcloth and ashes of suburban angst and live it up a little. A girl can’t live on pie and penance alone.

★ ★

PG-13. At area theaters. Contains thematic material, brief violence and sexuality. 111 minutes.