If you ever meet August Wilson, and you ask him how his day was, and he begins to tell you, commit the answer to paper. The story will certainly amuse, and may win the Pulitzer Prize. In a Broadway career now entering its third decade, Mr. Wilson has demonstrated that he views stories the way gourmands dream about courses: the more and the richer, the better. Plots, for Mr. Wilson, are grand exercises in storytelling. So are subplots.

“Gem of the Ocean,” the ninth play in Mr. Wilson’s ten-play cycle about the black experience of 20th-century America, bulges at the narrative seams. He spins his tales – about the vexations of freedom in the North, about memories of slave times in the South – with his customary knack for melody. Long riffs and short bursts, deep rumbles and an occasional trill: Mr. Wilson’s writing is less poetry than jazz. Call him the Coleman Hawkins of Broadway.

The play, which opened last night at the Walter Kerr, tends to mesmerize. Do you detect a hitch in the plot? An ill-formed character? An endorsement of vigilantism? No worries, just let the word-music move you. Take this speech, for instance. It’s from a conversation about whether a man should build a wall in his yard. Read it aloud to get the full effect:

“A thief ain’t gonna let a wall stop him. He gonna climb over and keep climbing over until he find out crime don’t pay. That’s the way you stop a thief. A wall ain’t gonna do nothing but make him mad.”

There’s an echo here of “Fences,” Mr. Wilson’s best play. In fact, the resonances with his other works abound. As usual, the setting is Pittsburgh (this time, in 1904). We are in the home of Aunt Ester (Phylicia Rashad), the spiritual matriarch of Mr. Wilson’s universe. She has been mentioned elsewhere but never seen. Rutherford Selig (Raynor Scheine), the traveling salesman and “people finder” first glimpsed in “Joe Turner’s Come and Gone” also pops up.

Like their predecessors in Mr. Wilson’s earlier plays (and their descendants in the world of Mr. Wilson’s plays), the characters stoop under the weight of history – personal, familial, and racial (which is to say, national). Aunt Ester is nearly 300 years old, dating back to the landing of the first slave ship in America. Her gatekeeper Eli (Eugene Lee) was a conductor in the Underground Railroad, as was his friend Solly Two Kings (Anthony Chisholm). At the beginning of the play, Solly, now nearly 70, gets a note from his sister in Alabama. The white authorities won’t let anyone leave. He wants to go set her free.

But another man has just made the same trip, in the opposite direction. Citizen Barlow (John Earl Jelks), a young man, new to the North, barges into Aunt Ester’s house in search of her “soul cleaning.” He has committed a crime, and needs to atone. Eli puts him to work building that fence, while Aunt Ester prepares to take him on a mystical journey to the City of Bones. It’s a kind of spiritual return to the experience of the slave ships, effected through chants, masks, and a sort of hypnosis.

Definitely not naturalism, this play. In last season’s “A Raisin in the Sun,” Kenny Leon showed a graceful manner with actors in a plain realistic setting. He’s done the same here, but the phantasmagoria falls flat. Mr. Wilson is also to blame, to be sure. He has crafted some convincing stage magic before, as in the ghost story “The Piano Lesson.” The disbelief this time is a little too heavy to suspend. (The problem isn’t solved by David Gallo’s scenery, towering walls and ceiling covered in a weird, gloomy blue-black lacquer; does Pittsburgh have a Little Transylvania?)

Mr. Wilson’s everyday storytelling proves much more winning. Early in the show, we hear about Caesar, the town official who wants to catch a thief. He sounds like a brittle embodiment of authority gone awry, John Ashcroft without the pious veneer. Then Caesar himself appears, and the surprise is delightful.

Caesar, it turns out, is the brother of Black Mary (LisaGay Hamilton), who cooks for Aunt Ester. And he’s just a constable, albeit one with plenty of power, and no hesitation about using it. He sounds like Sophocles’s Creon when he defends the primacy of the law. As played with extraordinary balance and skill by Ruben Santiago-Hudson, Caesar also becomes a figure of great comic menace. Mr. Wilson makes us recognize why he acts the way he acts, and makes him enormously funny without losing his fearsome side. It is a remarkable creation: Like Lymon, a secondary character in “The Piano Lesson,” Caesar steals the show.

As the ancient Aunt Ester, the gifted Ms. Rashad transforms herself once again. Here she is stout and grandmotherly, with a twitch in her left hand. She also abandons the lower two-thirds of her vocal range, leaving a high, spare delivery that somehow loses none of its power. Ms. Rashad does wonderfully by the role’s humor; alas, the oracular side of Aunt Ester plays right into Ms. Rashad’s worst (in fact, maybe her only unhelpful) tendency: pronouncing instead of talking, turning characters into statues of themselves.

The audience positively devoured Ms. Rashad’s performance, but there’s work just as fine on every side. Mr. Jelks gets Citizen’s earnest anxiety, maybe a little too completely; Mr. Chisholm has Solly’s rascally charm. Ms. Hamilton shines especially bright, particularly when Citizen decides she’d be an easy conquest. But it’s Mr. Santiago-Hudson who has the deceptively difficult path to walk, and walks it the best.

Even when it descends a bit too far into speechifying and hocus-pocus, Mr. Wilson keeps an eye on freedom and its discontents. Free life in the North hasn’t solved everybody’s problems. Of whites in the Civil War, Eli remembers, “They never said they was gonna help us. They said the war was gonna help us. After that it be every man for himself.” Some will hear this as a simple diagnosis of racial oppression, others will detect a broader complaint: A challenge, maybe, to the nation’s brave new philosophy of governance.

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