“Don’t you know you can’t go home again?”

— Ella Winter.

In Kenneth Lonergan’s new film, “Manchester by the Sea,” we learn, if we didn’t know already, that every small town in New England looks pretty much alike, with the exception of Bedford Falls, and Casey Affleck isn’t Jimmy Stewart; of course, in this film the protagonist is George Bailey, without Angel Clarence’s help.

“Manchester” is what they used to call a “slice of life” story, and so it is. Look around the town you live in, and there’s sure to be one or more Lee Chandler (a good Casey Affleck) — an assortment of Lee Chandlers in your local sports bar, or maybe fixing the stopped-up toilet in your house.

When we meet Lee, he is fixing stopped-up toilets, broken stoves and hanging windows, or taking out the garbage.

Lee is a “handy man” in a nondescript Boston neighborhood full of dirty windows and assorted snow-covered dumpsters. There is probably a better upscale neighborhood nearby, but Lonergan doesn’t show us one.

Lee is an expatriate from Manchester on the North Shore, where he once worked a fishing boat with his brother Joe (Kyle Chandler).

Lee starts out with a nice wife and three sweet kids, but Lee bears the mark of Cain, that which a mysterious God occasionally visits upon Biblical losers like Lot and Job, small timers compared to Lee.

Eventually a series of terrible, heartbreaking events fall upon him and the weight of it all becomes unbearable, so Lee flees to Boston and gets swallowed up in obscurity.

But that whimsical God apparently wasn’t through with Lee.

One day he gets a call that his brother Joe has died suddenly, and there is a matter of the fishing boat and a nephew. So when Lee goes home, and sits in on the reading of the will, he discovers that this brother so loved him that he left Lee with the guardianship of his son, Patrick (Lucas Hedges.)

Joe was his brother? He knew him how long? And he wants this loser to take care of his son?

Lee, barely able to hold onto his apartment super job or afford a decent haircut, declines the offer, but as nobody else wants the boy, he accepts, and tells his nephew that he’s taking him back to Boston to help him clean up apartments. Say what?

But Patrick is a clean-cut kid, the star of his high school hockey team, and has his own rock band. Did I mention that he’s cute and is currently having sex with two girls? And his uncle wants him to leave all this?

The film ends with too much left floating in the air, but just a hint bubbles up that things may work out well for both of them. There is the boat that Patrick inherits and adores, but it suffers a rotten engine.

Now Lonergan gives us a deus ex machina via the NRA that will surprise all.

“Manchester” has several problems: It’s slow, and Lee is no George Bailey, but it has the essential ingredient — heart — and that rescues it. In addition, it boasts a splendid cast: Michelle Williams as Lee’s wife, who has one stellar scene; Casey Affleck will probably replace his brother’s picture on their mother’s mantelpiece. His Lee truly is a troubled loser who nobody wants around; Lee is a terrible bore and a most difficult character to warm up to, but therein lies the challenge for an actor to play, and Affleck, to his credit, pulls it off.

C.J. Wilson is the good guy who still has a share in the boat and tries to keep Lee on his feet. He comes close to stealing his scenes.

Hedges as the nephew shines brightly, and Gretchen Mol as the boy’s mother, a reformed alcoholic turned suburban Christian house wife, wins us over. Lonergan’s script dawdles a bit but has a strong message, and that is it really does take a village to raise a child.

J.P. Devine is a former stage and screen actor.