Cast member James McAvoy arrives at the premiere of "The Conspirator" in New York April 11, 2011.[Photo/Agencies]

Mutants, it seems, are only as good as the creators assembling their chromosomes. And the mad scientists behind "X-Men: First Class" are real artists in the laboratory.

Director Bryan Singer's first two installments of the "X-Men" trilogy were superior adventures, about as smart and provocative as comic-book adaptations are likely to get.

After Singer left, the trilogy wrapped up with a dud, followed by a limp spinoff chronicling the origins of fan-favorite mutant Wolverine.

Now Singer's back as a producer and idea man for "First Class," a prequel that presents a clever, cohesive, exhilarating big-screen take on how those Marvel Comics mutants came together on opposing sides in the evolutionary battle.

Matthew Vaughn, another filmmaker adept at blending smarts and action ("Stardust," "Kick-Ass"), was wisely recruited as director and co-writer.

The result is one of the best Marvel adaptations, packed with action, humor, retro 1960s style that's both campy and sexy and a revisionist history lesson that puts the X-Men at the center of the Cuban missile crisis.

The young cast led by James McAvoy and Michael Fassbender is no match for Patrick Stewart, Ian McKellen and the rest of the grand ensemble Singer enlisted for the first "X-Men" flick in 2000.

Yet McAvoy has playful energy and unshakable nobility, while Fassbender captures slow-burning wrath and unflinching pragmatism, which nicely prefigure Stewart's august Professor X and McKellen's dogmatic Magneto.

Despite a jumble of screenwriters that includes Vaughn, writing partner Jane Goldman and "Thor" scribes Ashley Edward Miller and Zack Stentz, "First Class" is a focused, coherent story.

That's all the more admirable given the large cast, whose stories are woven together with enough immediacy and clarity that even Marvel newcomers can follow along without a playbill.

We're introduced to McAvoy's telepath Charles Xavier and Fassbender's Erik Lehnsherr, who can manipulate magnetic fields, as boys in the 1940s. Their vastly different upbringings underscore the differences that eventually will turn them from best friends to bitter rivals.

Charles grows up in a rich, privileged home, believing he's a freak of nature, the only one of his kind, until he meets shape-shifting mutant Raven (Jennifer Lawrence), the future Mystique character originated by Rebecca Romijn in the "X-Men" trilogy.

Raven and Charles forge a foster-sibling relationship, while Erik, a Polish Jew, suffers unspeakable tragedy during the Holocaust as the Nazis try to unleash the boy's power to control metal.

Charles and Erik team up in the early 1960s as part of a CIA operation against Sebastian Shaw (Kevin Bacon), a mutant who can absorb explosive energy and aims to set off a nuclear war to wipe out humanity so his kind can inherit the Earth. Bacon's a lot of fun, clearly having a blast playing the U.S. against the Soviets as puppetmaster of Armageddon.

Shaw is aided by bad girl telepath Emma Frost (January Jones, who's stunning in her skin-tight Bond girl-style outfits and adopts a suitably icy demeanor).

Among those initially fighting for the good guys are intrepid CIA agent Moira MacTaggert (Rose Byrne), her nameless team leader (a sadly under-used Oliver Platt), and mutants Beast (Nicholas Hoult), Banshee (Caleb Landry Jones), Havok (Lucas Till) and Angel (Zoe Kravitz).

But allegiances change, and the point of the prequel is to spell out who switched sides and why. At the heart is the break between Charles and Erik, and the filmmakers, clearly plotting a prequel trilogy, leave plenty of loose ends to tie up and a lot of room to introduce more X-Men mutants down the line.

The story also leaves off around the time the civil-rights movement starts to pick up steam, so the franchise's parallels between human racism and bigotry against mutants are bound to gain new resonance.

Many key questions about the mutants — Magneto's helmet, Professor X's wheelchair and his telepathic-amplifying machine — are explained. The film also features a couple of amusing cameos by stars from the "X-Men" trilogy.

The visual effects are solid, though nothing spectacular. Where the film really shines is in the design, taking the cheesy aesthetic of early James Bond films and doing the `60s up right with all the glam today's big studio bucks can buy.

If the studio can keep Singer, Vaughn and the rest of the "First Class" team together, there's a chance that this "X-Men" trilogy could evolve into a better one than the original.

"X-Men: First Class," a 20th Century Fox release, is rated PG-13 for intense sequences of action and violence, some sexual content including brief partial nudity and language. Running time: 130 minutes. Three stars out of four.