Most likely the first question to be asked by anyone who has watched the eye-popping, acrobatic tap dance routines of The Nicholas Brothers — who began in vaudeville, danced at The Cotton Club, but will live forever thanks to a slew of movies they made from the 1930s on through 1970 — is this: How did these two men preserve their bodies after so many flying splits, high-stepping stair sequences and rocket-fast, hard-tapping riffs?

The second question might be: Who and what did they draw on for their innovative routines, and how did they collaborate to choreograph one wildly inventive and spectacular number after another? Aside from the briefest mention of Bill “Bojangles” Robinson we are told nothing about this in the new Black Ensemble Theater musical, “My Brother’s Keeper — The Story of The Nicholas Brothers.”

When: Through March 26
Where: Black Ensemble Theater, 4450 N. Clark
Tickets: $55-$65
Run time: 2 hours and 20 minutes, with one intermission

Vincent Jordan (center) plays Cab Calloway, with Rueben Echoles (left as Harold Nicholas and Rashawn Thompson as Fayard Nicholas in the Black Ensemble Theater production of "My Brother's Keeper - The Nicholas Brothers Story." (Photo: Michael Courier)

Vincent Jordan (center) plays Cab Calloway, with Rueben D. Echoles (left) as Harold Nicholas and Rashawn Thompson (right) as Fayard Nicholas in the Black Ensemble Theater production of “My Brother’s Keeper — The Story of the Nicholas Brothers.” (Photo: Michael Courier)

As it happens, the primary focus of this show, which has been written and directed by Rueben D. Echoles, is on the powerful if sometimes troubled bond between the brothers — Fayard (Rashawn Thompson), the calm and steady older of the two, and Harold (Echoles), the angrier and less responsible one. Along the way we also follow the arc of their careers, the role of their loving parents and their own flawed marriages.

That is not to say there isn’t some impressively flashy dancing here, with the all-important staircases and ramps straight out of The Nicholas Brothers’ stylebook at center stage. There also is some fine singing and zesty portrayals both by the brothers themselves, as well as by one of their early champions, Cab Calloway (Vincent Jordan, so charismatic that you hope there is a Calloway show for him in the offing), and by the beautiful, talented and tragic Dorothy Dandridge (Taylay Thomas, a real looker, whose growth from groupie-like teenager to independent woman is expertly captured here). Dandridge, who married Harold, and was more or less abandoned by him when she chose to care for their brain-damaged daughter rather than institutionalizing her, became the first African-American actress to be nominated for an Academy Award for best actress (in the 1954 film, “Carmen Jones”).

Of course nobody can replicate The Nicholas Brothers’ astonishing, virtuosic routines; they were a “one-of-a-kind” duo. But while Echoles and Thompson are impressive in their faster-than-the-speed-of-light footwork and bold jumps, the script, as is often the case with BET shows, has a sort of paint-by-numbers quality. And the first act ends not with a bang but with a whimper. (Much of this can and should be revised for any future edition of this production.)

To be sure, the show makes the point that through almost every trial and tribulation the brothers’ devotion to each other was of the essence — something instilled in them from early on by their devoted parents (played by Dwight Neal and the warmly embracing Katherine Thomas). There also is a nicely played comic tension between Dandridge and Geri (the exuberant Jessica Seals), Fayard’s smart, snappy, non-show business wife.

Although the racism the brothers and Dandridge encountered is dealt with along the way (at one point Harold heads off to the more welcoming society of Paris), there is no mention of the fact that many of their film sequences were inserted into movies in a way that enabled producers to splice them out when they were being distributed to audiences in the South.

The 20 or so songs in the show range from standards (“Jumpin’ Jive,” “Take the A Train,” “Chattanooga Choo Choo,” “Sing Sing Sing,” “I’ve Got Rhythm,” and more, many with unusual arrangements), to eight songs penned by Echoles that move the story along. And as always, the ensemble sings and dances up a storm (decked out in a slew of laugh-inducing plaid jackets and spangly gowns), with music director Robert Reddrick and his band making a most joyful noise.

Taylay Thomas plays Dorothy Dandridge in the Black Ensemble Theater production of "My Brother's Keeper -— The Story of The Nicholas Brothers." (Photo: Michael Courier)

Taylay Thomas plays Dorothy Dandridge in the Black Ensemble Theater production of “My Brother’s Keeper — The Story of The Nicholas Brothers.” (Photo: Michael Courier)