Marc Kudisch, Mark Delavan, and Nathan Gunn Photo by Chuck Osgood

Baritones Unbound? When were they ever in a bind? In this concert with scripted narration, three of the world's finest baritones—Marc Kudisch from the musical comedy world, plus Nathan Gunn and Mark Delavan from opera, give us an immensely entertaining lecture on the role of the baritone throughout the development of vocal music and particularly musical theatre. Beginning with Gregorian chants and making their way through opera buffa and seria, grand opera and operetta, they arrive at the 20th century where they spend more than half of the 2-1/2 hour show (including one intermission). There we learn of the baritone's key role as male lead in many musicals of the last century as well as their popularity in pop, rock, and country music. The show includes a little rock and country, a little more opera, and a lot of musical theatre. There's something for every musical taste, so aficionados of any particular genre may find themselves wanting more of their favorite, but will be thoroughly entertained by the magnificent voices and the thoroughly charming and easygoing delivery of the trio.

The trio complement each other in voices and styles. Kudisch is the quintessential Broadway "bari-tenor," with a powerful voice that has a softer center inside. Delavan's bass-baritone is especially effective on the darker numbers featured in the concert, while Gunn has perhaps the most beautiful and purest baritone of the three. Kudisch's experience as musical comedy actor/entertainer makes him the natural to take the lead in the narration, but all three seem at home and having the time of their lives in this format, moving easily under David Dower's smart direction around the stage of Hershey Felder and Trevor Hay's set design of props from some of the shows referenced in the repertoire.

The show was conceived by Kudisch and written with Broadway's Merwin Foard, opera's Jeff Mattsey and the production's musical director and pianist Timothy Splain. This tour through musical history concisely connects many major works of the centuries and places them in the hands of these exceptional singers, giving the audience moment after moment of definitive performances of musical theatre's greatest classics, frequently and cleverly transforming solos into duets and duets into trios. From 18th and 19th century opera we hear both Mozart and Rossini's "Figaro" followed by a visit with Gilbert and Sullivan's "I Am the Pirate King" from The Pirates of Penzance, set up by a charming anecdote of Gilbert & Sullivan's failure to bring the score of that operetta along with them when they sailed to America for its premiere. The transition from operetta to musical theatre is represented by Romberg and Hammerstein's "One Alone" from The Desert Song, followed by the trio taking turns on the glorious "Ol' Man River" from Show Boat, including verses of biting social comment not always performed. It's at this point in the show when, at least for this musical theatre lover, the program really begins to soar.

Kudisch, who, like his onstage partners, is ever affable, relaxed and appearing to have a great time, tells us of the importance of Oklahoma! to the development of the musical comedy genre and he introduces it with a stunning "Oh, What a Beautiful Mornin'" on which the three take turns. We then hear that musical's "Lonely Room"—seldom performed outside of the show but a marvelous showcase for operatic bass-baritone Delavan. The three follow with a unique approach to Carousel's "Soliloquy," cleverly made into a trio. Kudisch takes the lead as Billy Bigelow, with Gunn and Delavan responding with additional thoughts as if Billy's musings are a conversation shared with friends rather than a solitary meditation.

Kudisch honors Alfred Drake with a rendition of "Where Is the Life That Late I Led?" from Kiss Me, Kate. The three acknowledge the rise of pop and rock music with segments saluting Frank Sinatra and Elvis Presley—singers of very different genres but baritones nonetheless. Acknowledging Sinatra's 100th birthday the day before the opening night performance, Delavan offered a sophisticated "I've Got You Under My Skin," before the trio took turns on "It Was a Very Good Year" in front of projections showing Sinatra at different stages of his life. (These were some of many effective projections by Christopher Ash, who also did the lighting design.) Presley is introduced with Kudisch doing "That's Alright, Mama." A juxtaposition of "It's Now or Never" with Gunn singing "O Sole mio" cleverly makes the point that, for all his pop success, Presley was an accomplished baritone.

Back in the musical theatre world, the trio pays tribute to Stephen Sondheim with an absolutely stunning set of his songs written for baritones. Called "Sondheim Tag Team," it begins with Delavan and Kudisch performing "It Would Have Been Wonderful" from A Little Night Music, continuing with Kudisch and Gunn doing Sweeney Todd's "Pretty Women," and concluding with Gunn and Delavan on "Agony" from Into the Woods. The set was an absolute dream for this Sondheim fan, as was Delavan's "Ballad of Sweeney Todd" later in the show.

Other memorable musical theatre moments for baritones from the latter 20th century include Lerner and Lane's "On a Clear Day You Can See Forever," followed immediately by 1776's "Molasses to Rum"—both introduced on Broadway by John Cullum, who goes unacknowledged here. Bemoaning the current decline in popularity of music written for baritones, they conclude with a stirring rendition of Jerry Herman's "I Am What I Am" from La Cage aux Folles. They return for an encore of "Folsom Prison Blues" saluting country's Johnny Cash. It seems more of an afterthought than an encore, but this is the only semi-misstep in a show that ought to be enjoyed by millions, whether on tour or through video and audio recordings we hope we will be made. (It would be a sensational PBS Pledge Drive program).

The awkward title of Baritones Unbound is the only real flaw in this magnificent concert. Baritones Rebound is more like it.

Baritones Unbound will play the Royal George Theatre, 1641 N. Halsted, Chicago, through January 3, 2016. Tickets available by phone at 312-988-9000 or online at theroyalgeorgetheatre.com.