Marvel continues its plans for world domination while its on-screen heroes battle against a foe bent on the same goal in the breathless Avengers sequel Age of Ultron. All the big names are back (with a few more are added to the mix) in a movie that provides non-stop action with some welcome sojourns that examine what it means to be a hero. Writer-director Joss Whedon continues to show a deft touch but some franchise fatigue creeps in the corners as the over-arching Marvel plot sometimes takes precedent over smaller character moments. Age of Ultron is still a remarkable juggling act with moments that’ll have audiences cheering – it just doesn’t clear the very high bar set by its predecessor.

The movie wastes no time and begins in media res, with the Marvel heroes knee-deep in an assault on a mountaintop Hydra compound in the snowy (and fictional) Eastern European country of Sokovia. A quick catch-up: the WW2-era super soldier Steve Rogers/Captain America (Chris Evans) leads the team with valour, aloof God of Thunder Thor (Chris Hemsworth) pounds things with his hammer (Mjilnor!), super-rich and super-snarky Tony Stark/Iron Man (Robert Downey Jr.) continues to peace-keep using advanced weaponry, and poor Clint Barton/Hawkeye (Jeremy Renner) tries to keep pace with superbeings using only a bow and arrow. A new wrinkle appears in the form of mysterious Natasha Rominoff/Black Widow’s (Scarlett Johansson) burgeoning relationship with Bruce Banner/Hulk (Mark Ruffalo). She’s the one tasked with singing the giant green Hulk a “lullaby” to calm him back down from his monstrous form.

Before Black Widow can do so, Hydra (a Nazi-like villainous organization) springs two new “enhanced” superbeings against the Avengers in the hopes of turning the tides in their favour (the villains always seem so outmatched against this super-team – case in point, they all fought Loki (Tom Hiddleston) in the first movie). The new foes are twins Pietro and Wanda Maximoff a.k.a. Quicksilver and Scarlet Witch (Aaron Taylor-Johnson and Elizabeth Olsen) who possess the powers  of super-speed and reality-warping telekinesis/telepathy respectively. The opening is chockablock with great moments (like Hulk being called into battle and Cap flipping a motorcycle) but, like the movie itself, strains a bit having to service so many characters and needs.

This sequence provides the heroes with Loki’s scepter – the MacGuffin around which the movie centres – and the fact that it appeared in the first film provides both a sense of continuity (good) and a sameness to previous iterations (bad). Loki himself doesn’t appear in Age of Ultron, and with such strong protagonists it actually becomes a necessity to have their inner struggles and demons become antagonists themselves, as no single baddie alone can stand up against Earth’s Mightiest Heroes. And so it is that the shape-shifting artificial intelligence Ultron (a silky smooth and glibly evil James Spader) takes corporeal form through Tony Stark’s peace-keeping plan of the same name. Originally intended to “build a suit of armour around the world” by Stark, Ultron quickly realizes that the best way to save humanity is to destroy it through an Extinction Level Event, thereby clearing the Earth for some new inhabitants.

It’s an intriguing concept that posits Ultron as the rebellious son to Tony Stark’s well-meaning but misguided father, with their deeply clashing worldviews providing much of the philosophical frisson. Ultron’s initial attack on Stark’s apartment (busting up a raucous and fun party that includes the inhabitants all trying and failing to wield Thor’s hammer, which is not a reference to a key party) is both creepy and fun, as Spader brings an omnipotent yet darkly humourous bent to his homicidal robot. From there it’s a series of escalating action sequences interspersed with technobabble and some blessedly quieter moments, as the Avengers try to battle shifting allegiances within and outside their group while trying to shut down Ultron before he destroys the world.

In the first Avengers Whedon finally established an agreeable cinematic representation of the Hulk, making Bruce Banner’s big green alter-ego that film’s breakout character and audience favourite. In Age of Ultron Whedon turns his attention to Hawkeye, making the relatively mundane hero self-aware (“I have a bow and arrow, none of this makes sense!”) and providing him with a backstory and motivation – including a reason to hang up his quiver for good. Johansson’s Black Widow also continues to thrive under Whedon’s pen, and her relationship with the soulful Banner provides a romantic sub-plot while Thor and Iron Man’s girlfriends are conveniently out of the picture (waved off in a funny and nearly 4th-wall breaking scene).

Further franchise elements must be served inevitably, and the movie does so with various levels of aplomb. The upcoming Civil War between Captain America and Iron Man is foreshadowed in a subtly menacing conversation between the two, while a less successful scene (seemingly from a different movie) sets up Thor’s eventual Ragnarok (a.k.a. his next solo adventure). There’s also a new “enhanced” hero brought into the fold in the 3rd act – the powerful and benevolent android Vision (Paul Bettany). His appearance further takes the Avengers series into cosmic and far-out territory, but the character’s brief arc and naivete play well in the context of the film, making his presence is a welcome one.

In all, the Whedon magic is still there (if slightly diminished) and Age of Ultron serves up satisfyingly clear-headed action interwoven with well-liked characters that it’s hard to fault the movie too much in its off moments. Hulk vs. Iron Man is a mid-film delight and the large-scale climactic showdown has at least a few moments that’ll bring a smile to the most jaded fanboy’s face. If The Avengers was a homerun that cleared the park, then Age of Ultron is a solid triple. It proves to be propulsive yet occasionally hollow – but

whenever the movie stumbles it quickly recovers with a well-placed line or thrilling action beat. We come for the characters and their interactions, and thankfully they’re mostly well served by Whedon’s typically funny and busy script. In this cinematic Age of Heroes we find ourselves in, the Avengers continue to remain at the top of the heap.

Avengers: Age of Ultron (2015)

Director: Joss Whedon

Runtime: 141 minutes