If you've seen the trailer for ‘‘Labor Day,’’ Jason Reitman’s film based on the novel by Joyce Maynard, then you've caught a glimpse of a new breakout star, who threatens to upstage even the estimable Kate Winslet and Josh Brolin.

No, we’re not talking about young newcomer Gattlin Griffith, though he gives a lovely performance.

We’re talking about the peach pie.

Seldom has a baked good assumed so prominent an onscreen role as in this film, where it serves both as catalyst and as metaphor, for, um, sex. Plenty of movies have displayed food worshipfully, but this scene more aptly recalls that moist clay on the potter’s wheel in ‘‘Ghost,’’ where ceramics were quite beside the point.

Alas, both that clay and this pie hold together better than ‘‘Labor Day’’ does.

Reitman is a talented filmmaker, as you'll know if you've seen ‘‘Juno’’ or ‘‘Up in the Air,’’ to name just two. But those movies had key elements that ‘‘Labor Day’’ does not: Humor, and edge.

It’s understandable why there’s no humor here; it’s the story of a seriously depressed, divorced mother and her preteen son, and how their lives intersect one summer with an escaped convict, for a Labor Day weekend that will change all of them. Not much comedy there.

But the lack of edge or irony is more serious. Reitman is so sincere in his presentation of this tale that we feel rather smothered by it. It doesn’t help that the narration -- by Tobey Maguire, as the grown-up son looking back -- is often unnecessary, pounding in a point that we already got.

And the prominent flashbacks, while occasionally useful, are also downright confusing at times. They make you want to go home and read the book, because it becomes clear that a book would do so much better a job of fleshing out these characters -- and more importantly, explaining their actions.

None of this takes away from the very appealing performances of Winslet and Brolin, not to mention the sensitive Griffith. At times, you don’t even care that you don’t quite believe what they’re doing. You’re just enjoying watching them do it.

Winslet plays Adele, a mother whose depression makes her almost a hermit in her cluttered home in a New England town (gorgeously evoked in its summer glory by cinematographer Eric Steelberg.) We meet her and her seventh-grade son, Henry, as they’re embarking on a shopping trip for school clothes.

At the store, they’re approached by a muscular, menacing man with a bloody wound. He asks them to take him home and let him rest. ‘‘Frankly, this needs to happen,’’ he says.

At home, Frank ties Adele to a chair. But from there, he departs from our preconceived notions of escaped-convict behavior, making a pot of chili that Rachael Ray would love, and spoon-feeding it to Adele. As the weekend proceeds, Frank, who we learn was convicted of murder long ago, fixes the squeaky floorboard. He cleans the gutters and irons the clothes.

It gets better yet. When a neighbor delivers ripe peaches, Adele’s ready to throw them away, but Frank has another idea: baking the best-looking pie you've ever seen. ‘‘I want to talk about crust,’’ he tells mother and son, giving little tips like how crucial the salt is. Watching the pie rise in the oven, we want nothing more than to reach in and touch it. We wonder if there’s any vanilla ice cream around...

Oh right, the movie. Well, it’s not hard to see how attractive Frank seems to Adele. Still, things move awfully, even implausibly fast.

The drama heightens as we learn more about why Adele suffers the way she does, and why Frank ended up in prison. Thanks to some heartfelt acting -- particularly from Winslet -- we stay focused.

But it’s hard not to feel that this movie could have been so much better than it turned out.

Something we won’t say for that pie. That pie is perfect.

Two and a half stars out of four.