Say what you will about X-Men 3: Last Stand, and what you'd mainly say is that it wasn't very good, it did at least leave the mutant world in an interesting state. So the obvious course of action was to forget about it entirely, do a Wolverine prequel and then this general X-men prequel, with a young Professor Xavier and Magneto knocking around in their formative years. Potentially a dodgy move, with the franchise in danger of vanishing up its own behind, as would perhaps befit the fourth/fifth, depending on how you're counting, instalment in the franchise. That's it turned out so well is a welcome surprise.

This goes all the way back to a young, pre-wheelchair Xavier befriending everyone's favourite blue shape shifter Mystique, forming a brother/sister like bond, before going on to show us a young Erik Lenhsherr being "persuaded" into developing his powers at the ruthless Nazi hands of a Mengele-style nuttier who will go on to be known as Sebastian Shaw (Kevin Bacon).

Jumping forward a few years to the height of US/Soviet cold war tensions, we rejoin Michael Fassbender's proto-Magneto doing a spot of Nazi hunting, in an attempt to track down Shaw. Meanwhile, Shaw has gathered a small gang of dangerous mutants, known as the Hellfire Club, and is busy being rich, playing the Americans and Russians off against each other and being an all round bad egg.

Xavier's called on by the CIA as an expert in mutations after the agency suspect something extra-human is going on with the Hellfire Club members, and soon he crosses paths with Shaw co-incidentally at the same time as Magneto does. Saving Magneto from certain death at the hands of the suddenly all powerful mutant Shaw, the two form a believable bond that retroactively makes their respect for each other in the previous films make sense.

They team up, somewhat reluctantly, with the government in a bid to hurriedly find and train a team of mutants to go up against Shaw's squad, including a young Hank 'Beast' McCoy, Cyclops' relative of some yet to be determined nature Alex 'Havok' Summers, and the ironically named Darwin, given the series' chronic misunderstanding of the concept of evolution.

I suppose I ought to get the negatives out of the way first. The basic plot feels familiar, and is somewhat hackneyed. A number of the supporting cast of mutants seem to be introduced only to sling some fancy powers around, and have paper-thin characterisation. There's a few scenes, particularly early on with Erik's Nazi hunting, that would have been much more impactful without the thumping soundtrack accompanying it, although admittedly that might have put it's 12A certification at risk.

Everything else is vastly enjoyable. James McAvoy and Michael Fassbender give tremendous performances and create a believable basis for respect and friendship that's been missing all along, and both have great fun with the roles. The scripting of both characters is spot on, and it's one of those film where we can not only understand exactly why the bad guy (Magneto, in this case) forms the philosophy he goes on to act on, and more than that, sympathise with it more than Xavier's nominal "correct" course of action.

As for Kevin Bacon, well, he's an absolute riot to watch. I had for some reason feared a reprise of his Hollow Man take on things, which would not have been pleasant, but his Sebastian Shaw is a tremendous bad guy - as good a comic book villain as there's been, I'd say. The action is well handled, and doesn't feel like a layer of plot polyfiller as can be the case, and director Matthew Vaughn keeps up his track record of not having made a film I haven't loved.

It's certainly the best of the many comic book adaptations to appear this year, and indeed it's the best I've seen in a long time. Highly recommended.