“X-Men: First Class” is a huge improvement over the previous entry, “X-Men Origins: Wolverine,” and it’s also the best film in the series since “X-Men 2.” It’s breezy fun, the special effects are terrific, and the emphasis on character this time around makes for a more involving prequel. With Wolverine shoved to the side, this fifth movie and the second prequel in the long running franchise, many other characters get their chance to shine.

The primary focus of “First Class” is on Charles Xavier/Professor X (James McAvoy) and Erik Lehnsherr / Magneto (Michael Fassbender) as we see the significant events which shaped and brought them together. But while Charles’ upbringing was a privileged one, Erik’s was unbearably tragic as he and his parents were imprisoned in a World War II concentration camp. Erik’s ability to control magnetism becomes evident early on, and this talent soon gets exploited by scientist Sebastian Shaw (Kevin Bacon) who commits an atrocious act in front of him. From there on, the driving force in Erik’s life is one of bloody revenge.

Prequels are tricky because we are naturally inclined to be against other actors taking over roles previously portrayed by Sir Patrick Stewart and Sir Ian McKellen. Then there’s that cynical feeling of studios taking this route just to save money. It was deemed after “X-Men: The Last Stand” that a fourth movie with the same cast would have been far too expensive to make. Of course, with a reported budget of $160 million, “X-Men: First Class” doesn’t sound like much of a bargain. Moreover, does anyone remember “Dumb and Dumberer: When Harry Met Lloyd?” Did you think audiences were going to be fooled by a Jim Carrey-less prequel? Anyone remember “The Flintstones in Viva Rock Vegas?” Heck, does anyone remember the first “Flintstones” movie? I remember seeing it, but the plot details escaped me once I walked out of the theater.

But what’s great about “X-Men: First Class” is the cast doesn’t need to worry about living up to the actors who inhabited the same roles before them. They get to approach these classic characters in a different light, and this frees them up from any restrictions which could have been imposed on them. Characters like Mystique and Dr. Hank McCoy are given more depth and complexity than ever before, and many surprises are in store for the audience as the script invests a lot of emotion in these characters including those bad mutants we rooted against in the past.

James McAvoy is excellent as the young Charles Xavier, and he looks like he had lots of fun making this prequel. Whereas Patrick Stewart’s Professor X was wise and mature, McAvoy’s is just getting started in his career and comes across as quite the ladies’ man. I also admired that while Charles is incredibly intelligent, we find his ego getting the best of him. So sure of all the things he is knowledgeable of, McAvoy does great work in making Xavier well-intentioned but not as open to mutants being themselves in the real world.

Erik Lehnsherr/Magneto remains one of the most fascinating characters in the “X-Men” universe. While he’s been the series’ chief villain and a megalomaniac, Magneto is simultaneously an anti-hero and has even been seen as a hero in the comic books. It’s hard not to feel sympathy for him considering the horrors he was exposed to in his youth, and it makes his future actions understandable, if not excusable. No wonder actors have so much fun in this role; you never know for sure the direction Magneto will end up taking. All you can say is, whatever he ends up doing, it will be to his benefit more than anyone else’s.

With movies like “Fish Tank” and “Inglourious Basterds” under his belt, Michael Fassbender is the perfect choice to play the young Erik Lehnsherr before and after he becomes Magneto. Fassbender has given performances deep with complexity and feeling; looking like the good guy at one point and then later turning into one seriously twisted individual. As Erik, he is great at showing the different layers to this character who is forever caught in a horrific moment he can’t get out of.

But one character who really gets expanded in “X-Men: First Class” is Raven whose shape-shifting abilities earn her the nickname of Mystique. Rebecca Romijn played Raven in the first three movies as a villain, and her character never got much in the way of psychological depth. Jennifer Lawrence, however, gets more to work with as we come to meet Raven at the time her allegiance to her “brother” Xavier begins to wane.

In Lawrence’s hands, she makes Raven/Mystique a strong female role model, one who is determined to be open about who she is and not be ashamed of it. While hiding herself in human form, as she is encouraged to do so by Charles Xavier, Raven’s frustration at appearing in public as someone other than herself is beginning to take its toll. Lawrence is riding high on some incredibly strong performances, and she continues to show how far her acting chops can stretch.

With Bryan Singer returning to this franchise as a producer, I’m sure he had a good hand in getting this particular entry focused more on character development. Each character is shown to be suffering through conflicted emotions as to what path the mutant race should follow, making them no different from the humans who deal with many of the same issues. Mutants are seen as the next stage in human evolution, but the haunting question of whether this will be to humanity’s best interests or detriment always hangs in the air.

But the person who deserves the most credit for “First Class” is its director, Matthew Vaughn. Coming off of the gleefully rebellious “Kick Ass,” one of 2010’s best movies, he manages to bring a lot of inventive energy to a franchise in desperate need of it. Vaughn also makes the special effects benefit the actors instead of just overwhelming them. What made the first few “X-Men” movies so special was the amount of emotion they generated, and the same thing is definitely the case here. It’s our connection with these characters which makes the action set pieces all the more exciting.

If there are any problems with “X-Men: First Class,” they come in the last half as the filmmakers become overly concerned about bringing the characters in line to where they are at in the first “X-Men” film. This was also a big problem with “X-Men Origins: Wolverine” even though that prequel was much more convoluted. It would have been nicer to see the friendship between Charles and Erik get expanded instead of just ending this one with them taking opposite sides. Then again, perhaps it still could be expanded on in future installments.

Kevin Bacon, always a terrific actor, is perfectly detestable as the movie’s most irredeemable villain. At the same time, I wished the writers had expanded on his character more. Compared to the others, Sebastian Shaw threatens to be a little too one-dimensional in his actions. If Sebastian had more complexity to him, it would have made the transition of power between him and Erik all the more believable and compelling.

Other strong performances come from Rose Byrne as Dr. Moira MacTaggert and Nicholas Hout as the highly intelligent yet shy Dr. Hank McCoy. On the other hand, while January Jones is amazingly beautiful as Emma Frost/White Queen, her one-note delivery of dialogue is one of this film’s major detriments.

“X-Men: First Class” is a prequel done in the same spirit of J.J. Abrams’ “Star Trek,” and it’s proof you don’t need Wolverine present to make a good “X-Men” movie. This is a reboot which works to everyone’s advantage, and I am eager to see what comes next.

By the way, don’t bother staying through the end credits. There’s no post-credits sequence, so take care of that urine ache ASAP.

* * * ½ out of * * * *