“Marcus; or the Secret of Sweet,” the final installment in Tarell Alvin McCraney’s poetic Brother/Sister trilogy, is like a song you don’t want to end.

Director Marion McClinton’s magical staging, which opened Saturday at the Guthrie Theater, is a rare work that will be long remembered. McClinton, an expert interpreter of August Wilson, also is a master of the works of McCraney. The director has harnessed the talents of a young company of players into a beautifully acted, sweetly affecting production that is elegantly designed by Andrea Heilman (sets), Kalere Payton (costumes) and Michael Wangen (lights).

The 80-minute one-act, produced by Pillsbury House Theatre and the Mount Curve Company, continues characters and plot lines from the other plays in the trilogy — “In the Red and Brown Water” and “The Brothers Size.”

“Marcus” orbits Marcus (Nathan Barlow), 16, the son of Elegba, now deceased, and Oba (Jamila Anderson).

As he grows into his sexual identity, Marcus has haunting dreams of his father. He asks around for help in interpreting the dreams. But everyone turns away from him.

Marcus has real-world complications as well. His relationship with friends Shaunta (Joy Dolo) and Osha (Lauren Davis) gets messy because of Osha’s feelings for him. A rough, studly stranger named Shua or Joshua (Darius Dotch) enters the scenario.

Barlow, who has grown up onstage in the Twin Cities, delivers a breakout performance that is grace-filled and revelatory. He handles his two major monologues, both Shakespearean in their heft, with charisma and aplomb, inviting us into his heart, his hopes and his reveries.

But his brilliance is far from solitary. We expect great things from James A. Williams, who plays Ogun Size, and from Aimee K. Bryant, as Osha’s mother, Shun. They do not disappoint.

All the players in “Marcus,” who sit at the side of the stage when not performing, have moments when they light up the stage with their individual fireworks.

Thomasina Petrus weaves her words like a vocal magician as community elder Elegua. Now you hear her, now you don’t. What she says out loud is as important as what she delivers sotto voce. She has perfect timing and a risible cadence.

Davis, who has lit up the stage at the Children’s Theatre and is most at home in Shakespearean characters, does a sterling job as the sassy Osha.

Dolo is a delightful discovery. She is pitch-perfect as Shaunta, Marcus’ protective BFF. Her turn is gorgeously funny and affecting.

Anderson, as Marcus’ mother, also is showing colors and notes she has never shown before. She’s rich.

Mikell Sapp is all fire and sass as Marcus’ school buddy Terrell. Ahanti Young gives muscular body to the ghost of Oshoosi, and also sits in as an onstage percussionist, enhancing the play’s atmospherics.

Dotch’s predatory character, with his cap pulled down low, is etched in memory.

“Marcus” is not without nits. It wraps up the series by referencing the other two productions in pictures. That video element is cute but not on the order of what comes before it.

This “Marcus,” a play that manifests McCraney’s abundant creativity, is sublime.