It’s pretty rare for a movie franchise to actually improve with age. Usually, a film series is borne from single inspired film that becomes embellished with a number of sequels, creating almost its own mini-genre unto itself.

Frequently, however, these sequels are merely a rehash of what made the original movie so spectacular, with each subsequent sequel offering diminished returns until the franchise is eventually killed off.

With "The X-Men" series, however, apparently conventional rules don’t apply. While the franchise has certainly had its small bumps in the past, 2011’s "X-Men: First Class" proved the it still had plenty of life in it. Now, with the recently released "X-Men: Days of Future Past," it may just be that we’re witnessing the best film in the entire series.

Cleverly integrating both the original X-Men as well as their younger selves that were introduced with a new cast of actors in "X-Men: First Class," the film’s plot involves a bleak future in which the X-Men find themselves on the brink of extinction. An army of mechanical bounty hunters designed to exterminate mutants dubbed "Sentinels" have become an insurmountable force, and threaten to enslave all of humanity.

Mankind’s only hope involves a plan sending Wolverine (Hugh Jackman) into the past to convince a younger Professor Xavier (James McAvoy) and Magneto (Michael Fassbender) to change the course of history so that the government-funded production of these death-dealing Sentinels, and their subsequent reign of terror, can be prevented.

Notably, "X-Men: Days of Future Past" represents the return of Bryan Singer to the director’s chair for the first time since 2003’s "X2: X-Men United," the series’ previous high point. With "Days of Future Past," the filmmaker once again shows us why he was responsible for the series’ success in the first place as this current installment gives the director the opportunity to redefine what a superhero blockbuster is supposed to look like. It’s as if the filmmaker was reinvigorated with the opportunity to flex his directing muscles back on his home turf, and the resulting extravaganza is packed with entertainment value on a number of levels.

In fact, the film almost feels overstuffed, featuring two generations of X-Men united for a common cause, as well as a narrative that unfolds with a level of complexity that stays true to a comic book’s pulp style of storytelling.

For example, the film exploits its own time travel scenario to cleverly integrate the X-Men into our nation’s history. Back in 1973, Magneto is imprisoned under the tightest security imaginable for being held responsible for the assassination of JFK, and must be broken out from inside the Pentagon. It’s a scenario that results in one of the film’s most remarkable sequences in which the newly introduced mutant Quicksilver (Evan Peters) manages to diffuse a potentially catastrophic gun stand-off with lightning fast speed and a sense of humor to match.

It’s here that the film’s excellent use of special effects becomes apparent as well, as Quicksilver’s abilities are given a show-stopping display. It reveals that the filmmakers are well aware that all the X-Men are all defined by their respective powers, and the movie unleashes those powers here with a spectacular fury. The only appropriate reaction is a profound sense of wonder, such as when Magneto raises the entire RFK Memorial Stadium up off the ground and drops it around the White House in an astonishing display of CGI work.

Rather than merely possessing a blockbuster-sized special effects budget, the screenplay’s attention to character detail, courtesy of Simon Kinberg is what really helps make this film soar. When Wolverine travels back in time, he discovers the younger Professor Xavier has basically become a junkie, reliant on a serum that blocks his powers and the overwhelming pain they cause him.

Later, when the younger Professor Xavier travels briefly to the future to procure moral guidance from his much older self (Jean-Luc Picard), it isn’t merely a nifty storytelling trick, but a glimpse into the character himself and the personal obstacles he must overcome to become the man he was destined to be.

The fact that this X-Men movie features cast members from both generations in parallel story threads also provides the added thrill of watching two potentially devastating battles happening simultaneously. The futuristic, apocalyptic scenes are appropriately bleak and violent here, and the X-Men meet some particularly grisly fates at the hands of the Sentinels -- fates that can only be undone by the actions of their younger selves. It gives the film a dark, dramatic weight that embellishes the parallel story set in 1973 in which the future of humanity rests in the balance.

This period setting of the ‘70s also allows all sorts of outdated, somewhat hilarious fashion styles to be paraded around as eye candy, proving the series hasn’t lost its sense of humor either. Wolverine soon discovers his claws are merely bone extensions back in 1973, and when Magneto later amusingly quips, "Just imagine those as metal," you can’t help but smirk affectionately in response. At the same time, there is also an undeniable pleasure in watching as President Richard Nixon and as his entire administration are under siege as their fate rests in Magneto’s vengeful hands.

With all these disparate elements being juggled in the air, it’s a small miracle that the filmmakers manage to keep it all together here. If the time travel mechanics get a little fuzzy or specific plots points become a little confusing along the way, it’s all just part of the package as the film becomes an overwhelming extravaganza. There’s almost too much to digest here all in one sitting, which ultimately only contributes to a degree of awe that "X-Men: Days of Future Past" successfully inspires.

Nathan Hurlbut is a free-lance filmmaker and a regular columnist for the Arts & Entertainment section.