“Drive Back Home” is a road comedy with a queer history subtext and a hard, melodramatic flourish saved for its finale.

It’s about a prodigal son and an estranged family that he fled the moment he was old enough to get away from the provincial New Brunswick town of his unhappy childhood. But in “Stonewall” era Canada, “tolerance” was hard to come by, even in the Big City.

A period piece “inspired by a true story,” it’s a reckoning-with-a-gay relative tale set in the very differernt Canada of 1969-70 (Phillip Forsyth is heard hosting “As It Happens” on the CBC, a job he left in 1969).

The whole village of Stanley turns out for the death of Perley Hinson Sr. But his no-nonsense widow (Clare Colter) unsentnmentally assures the priest that the whole village shows up for “every funeral.” Her sour expression and a cruel anecdote son Moses (Gray Powell) included in his eulogy tell us the old bastard won’t be missed.

Son Weldon (Charlie Creed Miles) is also also in attendance. But Perley Hinson, Jr. is nowhere to be found.

A sneering, abusive phone call from the Toronto police tells Weldon where Junior is. He’s in lock-up for having “sex with a man” in a public park men’s room. Perley Jr.’s looking at “five years” in those days of criminalized homosexuality, unless his brother comes to fetch him. Ontario’s not interested in prosecuting this crime any more, even if its cops don’t agree.

Weldon can’t go. “I’ve got work tomorrow.” He won’t. But his mother won’t hear of that. And after asking if “they speak English in Quebec” and stockpiling gas cans in the worn out F-100 that is his assigned company truck — because he’s told “No, they speak French” and he’s frightened by that — Weldon takes his first-ever long journey away from home to free a brother he doesn’t have much to do with.

Perley (Alan Cumming) is embarrassed that his brother has had to come and furious that the cops lost his nice loafers. He’s a hair-dyed dandy in colorful coat and jacket, ascot around his neck and Russian fur hat. And he’s dealing with a lot.

Not only was he beaten in custody, but his answering machine reveals that he’s lost his advertising job in his absencce. And then he has to explain the cost of a nice Toronto apartment and this newfangled answering machine to his “dumb hick” brother, who thinks he’s an “idiot” for living like this.

But they both do what Ma wants, so off down the road they go — a long haul that turns into a multi-day ordeal thanks to winter weather, a balky truck and misadventures along the way.

Back home, their mother and Weldon’s wife are putting up with less tolerant members of the family and hoping for the best. Because dealing with Perley, who likes drinking and hooking up, in that cultural climate has always been fraught.

And every so often, Weldon’s dreams give us a glimpse of the biggest trauma of their childhood, a violent night fleshed-out, bit by bit, in writer-director Michael Clowalter’s (“Tenant” was his) sentimental, sad with sharp edges screenplay.

“Drive Back Home” dawdles a bit for a road picture. The slow pace is a product of leaving room for DIY car repairs, Canadian roadhouse meals and grace notes like an impromptu “confession” to a non-English-speaking Quebecois (Guy Sprung).

That deliberate pacing makes the melodramatic, violent and yet touching finale more jarring.

But Cumming is always in-the-pocket “real,” first scene to last. Every moment of Perley’s live-for-the-moment behavior is plausible in Cumming’s hands, every hint of “had ENOUGH of this” abuse is an easy sale.

He and his fellow Brit Creed-Miles (“Harry Brown,” the gangster film “Wild Bill”) have great, abrasive chemistry and we believe them as ill-tempered, mismatched siblings who just might recover the tug of “family” when the chips are down.

They make this odyssey a tense and testy ride that turns touching, just as we hoped it would, just when we least expect it.

Rating: R, graphic violence, sex, alcohol abuse, profanity

Cast: Alan Cumming, Charlie Creed-Miles, Clare Colter, Gray Powell, Guy Sprung and Gord Rand.

Credits: Scripted and directed by Michael Clowalter. A Good Deeds Entertainment release on Amazon Prime.

Running time: 1:40