Husband-and-wife actors Jim Cada and Susanne Egli, who have coached theater at Minnetonka High School for 20 years, play a long married couple in "On Golden Pond" at Minnetonka Theatre. (Jim Cada)

He’s a pain in a rut.

An inveterate curmudgeon, retired English professor Norman Thayer (Jim Cada) is all gloom-and-doom as he spends his last summer at the family’s lake cabin in Maine. He and his wife, Ethel (genial Susanne Egli), have been together for 48 years, and she knows that it’s a fear of death that makes him undercut nearly everything she says as he approaches his 80th birthday.

After humoring him for a bit, Ethel tells him: “You really are the sweetest man in the world. But I’m the only one who knows it.”

“On Golden Pond,” the Ernest Thompson play best known for its 1981 film version headlined by Henry Fonda and Katharine Hepburn, is up in a not-to-be-missed production at Minnetonka Theatre, the intimate, well equipped community playhouse attached to Minnetonka High School.

Languid like a beach vacation, Trent Boyum’s production is suffused with the sounds of loons and an air of inevitability. Like all idylls, these times are fleeting. But the staging is bittersweetly entertaining, inviting us into the memories of a couple and family as they wrap up a season of life.

A long-married acting couple who have coached theater at Minnetonka High School for 20 years, Cada and Egli have easy mastery of their copious lines. But it’s their chemistry that makes this “Pond” twinkle. Their dialogue — I’m loath to call them arguments, since Ethel never really takes the bait — rings with truth and knowing.

Ethel has a deep empathy for her husband and sees the cowering man in need of an embrace under the gruff exterior. In fact, there’s a moment in the show, after Norman has tried to gather some strawberries, that’s quite touching.

And even though Cada’s Norman is macabre, the actor demonstrates an emotional economy and restraint that leavens the gloom of his view.

These lead performers draw their retrospective characters with distinction and an understanding that their coping styles spring from their personalities.

Ethel is all sunshine and hope, using positive thinking to brunt the power of the inexorable march to what she no doubt sees as the light. For Norman, the end is all darkness and oblivion. That is, until the story changes up when daughter Chelsea (Laura Baker), from whom Norman has been estranged, bangs on the door. She wants to make a quick introduction of her beau, dentist Bill Ray (earnestly mustachioed ringer Chance Carroll).

Bill is a divorced dad with an adolescent son, Billy (Carter Monahan), who is walled off with attitude but might just be the perfect vessel to bring new life and joy back to Norman. The “Pond” cast is rounded out by Michael Quadrozzi as the sincere boat-delivering mailman.

The supporting ensemble does beautiful work at Minnetonka Theatre. Monahan captures Billy’s sulkiness and dyspepsia, even while introducing Norman, the miserable geezer who is his senior mirror, to new (now old) slang.

Baker is no nonsense and focused as Chelsea seeks to rectify a lifetime of grievances against the dad she calls by his first name. Carroll never gets ahead of his lines, and his Bill proves a worthy match for Norman.

Altogether, this cast makes this “Pond” dapple like evening light dancing on the water’s surface.