A mind-blowing, shape-shifting, metal-bending prequel that delves back into X-history. We see how young mutants Charles Xavier (James McAvoy) and Erik Lehnsherr (Michael Fassbender), aka Professor X and Magneto, worked together as students before the lifelong rift appeared between them. In league with their lava-hot cast, the Kick Ass writing-directing team of Jane Goldman and Matthew Vaughn ensure that this X hits the spot.
The best mutant melee since X2, this breathless prequel stylishly reinvigorates the franchise, despite its undercooked CGI and over-clocked pacing.
It's the swinging 60s and telepathic brainbox Charles Xavier (McAvoy) and his shape-shifting pal Raven (Lawrence) are coming to terms with their mutant powers.
Contacted by CIA operative Moira MacTaggert (Byrne), who is tracking malevolent mutant mastermind Sebastian Shaw (Bacon), Xavier agrees to share his expertise on mutation.
Meanwhile, Holocaust survivor Erik Lehnsherr (Fassbender) is using his mutant powers to cut a bloody swathe through Europe and South America in the search for Shaw, who subjected him to unspeakable horrors in a Nazi concentration camp.
As Lehnsherr's activities put him on Xavier's radar, the benevolent boffin manages to convince the magnetic avenger to join the team of mutants he's assembling to take Shaw down.
Using technology devised by brilliant mutant Hank McCoy (Hoult), the duo begin to recruit and train a genetically gifted crop of youngsters, and as Shaw unleashes a devilish scheme to wipe out mankind, it's up to these 'X-Men' to save the day.
There's much about First Class that's X-ceptional, not least of all the casting of the equally excellent McAvoy and Fassbender as the two men whose warring ideologies give X-Men stories so much more depth than the average comic book yarn.
Since X-Men creator Stan Lee has always maintained that Xavier and Lehnsherr are based on Martin Luther King and Malcolm X, setting the story at the height of the civil rights movement is something of a master-stroke.
It also allows the director to indulge in some groovy 60s referencing, from depicting Lehnsherr as a smooth 007-style assassin to setting the action-packed finale against the backdrop of the Cuban Missile Crisis.
Scripted by Vaughn's Kick-Ass collaborator Jane Goldman, it's ironic that the most youth-orientated X-Men adventure is also the most adult.
Along with startlingly effective moments of violence and a slinky sexiness that's likely to leave comic book nerds needing a lie down, there's even the dropping of a well-timed F-bomb in a priceless cameo.
X-Men films have always been about the strength of the ensemble cast, and Vaughn has put together a fine group of young actors who work together with an easy charm; Hoult and Lawrence's tentative romance being particularly effective.
Bacon is also on fantastic form as the sneering arch-villain and although January 'Mad Men' Jones is fairly forgettable as his diamond-skinned sidekick Emma Frost, Jason Flemyng's teleporting terror Azazel is scary enough to ensure the bad guys are satisfyingly formidable.
Capturing the spirit of the previous films, without desperately struggling to achieve continuity with them, Vaughn gives these familiar characters an origin story that rings true, nodding to past instalments, without being overly reverent.
Unfortunately, it's some wobbly CGI reminiscent of the disappointing X-Men Origins: Wolverine, and a rushed pace that prevents First Class being the superhero equivalent of JJ Abrams's fantastic Star Trek reboot.
With an extra six months in post-production and a less ramshackle edit, this could easily have been the best X-Men movie ever.
It's pretty close regardless, and any film that sees Professor X downing a yard of ale before chatting up girls down the pub has classic written all over it.