The setup:

I guess if you've never seen Bernard Slade's romantic comedy Same Time, Next Year, which spans decades during a love affair between two people married to others (on Broadway in 1975 with Ellen Burstyn and Charles Grodin; in the movies in 1978 with Burstyn and Alan Alda), you might find John Shevin Foster's romantic comedy Plenty of Time, which spans decades during a love affair between two people married to others, a pleasant diversion. Which it is, if for no other reason than that this time the couple is black, and the extremely personable actors make this hoary premise work better than it should.

The execution:

Playwright Foster says right off in his intro notes that he cribbed the idea for his comedy from Slade's play, which also raises the question, "Why bother?" Sure, the couple superficially transforms through the ages according to what's happening outside the Martha's Vineyard cottage owned by the girl's upscale parents, so there are references to the Black Panthers, afros, women's lib, Vietnam, the glass ceiling, racial inequality, AIDS, son-and-father conflict, mom-and-daughter conflict, the inevitable aches and pains of getting old – sort of a Sparks Notes grab bag of everything you'd expect from a time span that runs, or plods (depending on how susceptible you are to this type of sentiment), from the heady hippie days of 1968 through the corporate strictures of 2011.

However, being black for our two protagonists (the appealing duo Rachel Hemphill Dickson and Steven J. Scott) doesn't seem to influence their choices in any particular way other than following the playwright's dictate. Sure, at the beginning, Corey, a busboy at a tony summer party at the beach resort, pretends he's a Black Panther just to get into Christina's pants, and she's young and arrogantly entitled enough to let him. They both enjoy the frisson and the sex. Their weekend relationship is off and running for the next 43 years. Their being black just doesn't add anything significant to their stories, separate or together. They are not down for the struggle as much as down with each other.

Each time they meet, someone is different, prickly or a bit more mature, mainly from influences inside their shared short summer time, and it takes no time at all for us to wonder why they don't hook up permanently. They feed off each other, whether in support or sparks, but there's an insufferable sadness to the whole thing. We know they're destined to be together, but how can these two principled, decent people blithely disrespect their other, avowed partners? Do real people actually tune out their lives for a weekend every year and go off for great sex without consequences – or guilt? This was Slade's problem, too.

But since this is whimsical romance, a fairy tale, if you will, we go with it without protest. The two leads are so good at preening or suffering or being cozy, we suspend disbelief and actually root for them to get it on – once again into perpetuity.

Scott does “decent” just about as well as anyone on a Houston stage. He's a lithe, lean stage presence (and, considering he spends a great deal of time in his tighty-whities, that is a blessing), and his character is always forthright and upstanding, even when he's purring for more of Christina's “stuff.” He's slinky and very fine. There's a lot of exposition in this play, with the years flipping by like a calendar in a '30s movie, but Scott handles these awkward passages with polished naturalness. Dickson must play an unappetizing first scene in which she's manipulative and whiny, so it takes longer for us to get on her character's side, but she soon prevails with, again, a natural, believable style that deepens as the play evolves. Thanks to director Eileen Morris, they play off each other like longtime lovers.

Adrian Washington's sound/video design, which highlights the years passing between scenes, is a perfunctory reel of celebrities, epochal events and song clips (assassinations, Michael Jackson, 9/11, the premiere of The Oprah Winfrey Show, Monica Lewinsky, the Challenger disaster, numerous covers of Jet), but what else could it be? Nothing shown has much, if any, effect on Corey and Christina's life as depicted by Foster. It's a nostalgic video tribute and draws some appreciative audience “awws.” The short clip of Prince singing “Purple Rain” got applause. It primes the scenes for the apt costumes, nicely conjured by Andrea Brooks. Lee O. Barker's holiday retreat set is as bland and nonthreatening as the play, and never changes as the years go by: a cassette player replaces the record player; the painting above the bed is swapped out, but that's about it.

The verdict:

In the final sequence, after previous prompting from Corey, who's now a retired prominent district attorney about to fly off to South Africa to work for the disenfranchised, Christina has become a celebrated author. Suddenly an overnight success, her best-seller, Plenty of Time, is based on her evergreen relationship with Corey through the years. “It works,” Corey crows at her with pride, “because it's real.” Wish Foster's play was.

Plenty of Time runs through June 5 at The Ensemble Theatre, 3535 Main. For tickets, visit ensemblehouston.com or call 713-520-0055. $23 to $50.