In a second act moment of comedic relief, King Arthur and Queen Guenevere take a break from lust, jealousy and guilt to musically speculate about “what the simple folk do” when “they’re blue.” Yep, things rhyme. There’s a repeating melody. Arthur even pulls out an Irish jig. But the number fulfills its function: The audience sees the legendary couple at its most human, affectionate and goofy — making the inevitable fallout even more painful.

The interesting and challenging thing about “Camelot” is that the audience already knows the basic story (in case you missed the memo, Guen runs off with Lance). They at least know the ending, which starts the first act before a two-hour flashback. The musical’s purpose, in the words of Merlin, is to show Arthur why both his dream of a revolutionary, chivalrous new order and his marriage have completely fallen apart.

The show does not definitively answer either question, but it certainly throws out some suggestions about human nature, none of which are very encouraging. This weighty sentiment struggles with the simplistic, bubbly music and dialogue in the piece, creating an ambiguous product — alternately entertaining, unconvincing, heart-wrenching and overblown. The cast and crew tackle the challenges of the script, both thematic and structural, with admirable energy, and at times they do succeed in creating both compelling dramatic tension and whimsical musical moments.

The story, which begins when Guen and Arthur first meet each other hiding in the woods on their wedding day, takes a little while to get going — early scenes between them are not as funny as they’d like to be. Part of this is an age issue: Lou Diamond Phillips and Rachel de Benedet just seem too old to run around giggling in the woods and acting like idiots, especially for Yalies familiar with this age group and their behavior. Lancelot starts out similarly caricatured, but far more hilarious, as a braggart Frenchman singing “C’est moi!” The actors perform far more convincingly as their characters mature and relationships deepen. In “How to Handle a Woman” (love her, by the way) Arthur’s melody begins to touch a real emotional chord, and Guenevere’s “Before I Gaze At You Again” later in the first act is heartbreaking. It seems things get better with age: The show’s oldest character, King Pellinore (Time Winters), is consistently witty, energetic and engaging, providing some slightly senile relief from the court’s tension.

If the show lacks some youthful spunk and irreverence, it makes up for it in experience. The complex set moves smoothly throughout the show to illustrate a variety of castles, town squares and enchanted forests, springing up effortlessly in the huge Shubert stage. The company numbers, while scarce, are well-choreographed and enthusiastically executed, convincingly transporting the audience to the throbbing, streets of Camelot. Especially fun is the tournament scene, where fight choreography and a lusty look from Lance to Guen spices things up. The unique combination of a professional space, crew and company provides a rich backdrop for the leads to play in, and is a special treat as a break from small-budget shows in college basements.

“Welcome to Camelot, where the tables are round and the relationships, triangular,” the show’s villain quips when he first sets foot in the musical reconstruction of the ancient legend. Mordred’s depiction is an accurate one: “Camelot” delivers a musical spin on the rich and familiar Arthur story that emphasizes the classic theme of romantic tension — and there’s a lot of it — but its geometric simplicity leaves an audience wanting something more.