X-Men: Days Of Future Past is a movie about the slippery paradoxes and mutable mechanics of time travel. Or, as James McAvoy’s Charles Xavier winningly puts it: "Future-shite." Although the storyline was conceived back in the early '80s for a two-issue run of the Uncanny X-Men comic book, it feels like it was dreamed up especially to solve the problem Fox faced after 2011's X-Men: First Class: what to do with a franchise that's been split into two timelines, with two sprawling casts? The answer, clearly, is to put all of it in a big pot and stir. Hence this vast-scaled, decades-leaping blockbuster, which throws in everything up to and including the kitchen sink. Plus the sleeker, leather-jumpsuit-clad kitchen sink of the future.

Marshalling it all is Bryan Singer, who seems to have himself jumped back in time. Whether he's been recharged by his decade away from the series, or by the prospect of eradicating some of the dodgier plot-turns made by Brett Ratner's The Last Stand — a movie that could now be retitled The Not Massively Relevant Stand — this is easily the most on-form and playful he's been since X-Men 2.

Remember the magnificent, bamf-happy Nightcrawler sequence that opened that movie? Wait until you see the mutant melee that kicks off this one. Pitting new heroes, the flashiest of which is Fan Bingbing's Blink (special ability: being able to play Portal in real life), against a teeming mass of unstoppable Sentinel robots (essentially a cross between the T-1000 and Louis Smith), it's a thunderous succession of nifty action beats. And that's just an amuse-bouche. Just as slick and inventive is Magneto's (Michael Fassbender) escape from a plastic Pentagon prison — one-upping a similar sequence from X2 — and a series of moments involving everyone's favourite nudie aqua-skinned shapeshifter, Mystique (Jennifer Lawrence).

Jumping between the future (light source: apocalyptic lightning) and the past (light source: lava lamp), the plot teeters on the edge of becoming exhaustingly knotty. Fortunately, the story distracts from any temporal muddles by zeroing in on three of the most charismatic characters in the X-universe: Wolverine, plus the younger iterations of Xavier and Magneto.

Charged with stopping Mystique from assassinating diminutive weapons-maker Bolivar Trask (Peter Dinklage) — a deed which will result in global extinction — Wolverine (Hugh Jackman) is hampered by obstacles: his claws are no longer metal, Magneto's being his usual bastard self, and his serene mentor Charles is now a thirtysomething depressive who won't get out of his dressing gown. In fact, the largest throughline of the film is dedicated to the latter (who doesn't seem to have yet thought up his snappy mutant monicker Professor X) attempting to get his mind-mojo back. Given all that, and the catastrophic peril that hovers over proceedings, there's a high potential for angst. But Simon Kinberg's script keeps things breezy; there are quips, in-jokes, Terminator references and, one of the high-points, a callback to the F-bomb dropped in First Class.

Following in the footsteps of Matthew Vaughn, who gets a story credit here, Singer has a blast going period. Richard Nixon is glimpsed on the cover of a National Lampoon magazine well before he becomes a key player in the climactic set-piece. The film deploys Zapruder-y handheld footage to jitter up a tense sequence in Paris. And while First Class tied the mutants' exploits in with US milestones like the Cuban Missile Crisis, Days Of Future Past gleefully rewrites the history books on a massive scale. Most notably by redecorating the White House lawn with the RFK Stadium.

With so much going on, and such a ferocious pace, several parts of the story feel undernourished. There's not nearly enough Ian McKellen. And it would be nice to learn more about villain supreme Trask. What is his motivation? With him so physically different, why would he choose to persecute others who are different themselves? And when the hell does he turn into Bill Duke, as seen in Last Stand?

But what we do get here is largely fantastic, not only re-energising old-favourite characters (and after his two spin-offs, Wolverine was in dire need of that) but introducing intriguing new ones. Most surprising is the fact that the super-speedy Quicksilver (Evan Peters), whose Ramona Flowers-y appearance did not inspire much confidence in marketing materials, turns out to be the coolest thing in the film. The sequence in which he leisurely takes out a squad of lawmen while stopping to taste soup makes Nightcrawler, in the words of Blackadder, look like an asthmatic ant with heavy shopping.

Verdict

The best X-Men film since the second one, this sequel/prequel/reboot trashes the '70s with elan. Some of the massive cast struggle to register (there's only a brief Storm), but what's here is all good. We want X-Men: Apocalypse, now.