RALEIGH - Predictability isn't usually something to strive for in a Broadway musical. But the best moments in "Monty Python's Spamalot" are those that come as no surprise.

And why not, when your source material is as clever as the 1975 film "Monty Python and the Holy Grail," the tale of the mythical King Arthur and his Knights of the Round Table?

The Knights who say Ni, the killer rabbit, the Black Knight, the French Taunter, Not so Brave Sir Robin — all re-emerge in this delightfully absurd adaptation of Arthur's quest. And in some cases, their mere appearance on stage set off gales of laughter in Tuesday's enormous and receptive audience.

"Grail" is the kind of movie people memorize, its key words and phrases serving as a mating call of sorts for Python fans to seek out their own kind. That's a blessing and a curse for "Spamalot," putting its actors under pressure to replicate the precise rhythms and inflections that made the British comedy troupe's storytelling work so well.

Few moments live up to their source in that respect. But Python member Eric Idle — who wrote the Broadway script and lyrics and co-wrote the music — adds ample compensatory treats.

Whereas "Grail" mocked moviemaking conventions, "Spamalot" skewers the cliches and excesses of Broadway theater. Almost every plot turn is an excuse for a splashy production number, from a showgirl fiesta in a Vegas-style Camelot to Lancelot's homosexual awakening and "The Song That Goes Like This," which cleverly skewers Andrew Lloyd Webber.

"Brave Sir Robin" gets transplanted from film, as does "Always Look on the Bright Side of Life." But the latter is from Python's mistaken Messiah tale "The Life of Brian," not "Grail," and without the crucifixes it loses its delightful irreverence and becomes merely earnest.

The production numbers are a bit lengthy, losing steam and slowing the story line, which also has a forced and unnecessary theater-oriented plot twist. And the new lyrics are surprisingly lazy in spots.

But where intellectual stimulation falters, eye candy provides a tasty distraction. The sets and costumes are among the most elaborate and inventive that Broadway Series South fans have seen, and Casey Nicholaw's choreography is lively and funny.

Veteran Broadway director Mike Nichols won a Tony for his "Spamalot" direction, and his appreciation for the petty, bickering and digressive Python style is clear.

He has gathered a satisfying cast for this Equity tour, led by Tony-winner Gary Beach ("The Producers") as Arthur. Beach's earnest portrayal serves as a fitting foil to the lunatics around him: the cowardly Sir Robin (James Beaman), the sheltered diva Prince Herbert (Christopher Sutton), the preening Sir Dennis Galahad (Ben Davis), the servile Patsy (Brad Bradley) and noble Sir Lancelot (Patrick Heusinger, who also portrays the French Taunter deliciously well).

Esther Stilwell's Lady of the Lake is among the highlights, ravenous for the spotlight and forcing her songs through a filter of ghastly stylistic cliches.

You needn't be a Python devotee to appreciate this self-described "Grail" ripoff. But if you relish silliness, Broadway's King Arthur will surely reign.