With ten previous films under their belt, Marvel wastes no time getting into action for Avengers: Age of Ultron. Beginning with a long, single take that follows each individual Avenger in action before bringing all six together in one epic shot as they race toward a fortress in the fictitious country of Sokovia, Avengers: Age of Ultron doesn’t feel the burden that The Avengers faced in setting up the team. They’re already a team, and one that works well together. The film’s quite aware that most audiences have seen at least its direct predecessor, so there’s no need to spend too much time filling viewers in on what’s going on.

The Avengers may begin the film as a solid unit, building off each other’s strengths to bring down bad guys, but they don’t stay that way. First up is an encounter with Wanda (Elizabeth Olsen) and Pietro Maximoff (Aaron Taylor-Johnson), a pair of Sokovian twins with a grudge against Tony Stark (Robert Downey Jr.). After being altered by Baron Wolfgang von Strucker (Thomas Kretschmann), Pietro is able to move faster than any other human; Wanda has the power to cloud minds and alter reality. As comic fans know, Wanda and Pietro – a.k.a. Scarlet Witch and Quicksilver – will eventually turn from enemies to allies, but it’s not an easy journey, and their hatred of Stark in particular is rooted in a very real sense of anger. Their reason for existence is out of a desire to protect their country from those who have helped turn it into a war zone, and that includes Stark.

The twins are also not the only characters whose well-meaning intentions go awry, though. Stark’s initial encounter with Wanda reinforces the trauma shown in Iron Man 3 following the Chitauri invasion in The Avengers; with the intention of protecting Earth from external threats, he develops [with some help from Bruce Banner (Mark Ruffalo)] an artificial intelligence named Ultron. Unfortunately, the introduction of an unpredictable element gives voice (specifically, of James Spader) to their creation, which leads Ultron to create an army of robotic bodies while telling the Avengers the only way to save Earth is to destroy the Avengers. As Ultron escapes across Earth, the Avengers follow to Wakanda, Korea, and back to Sokovia as they attempt to get ahead of Ultron.

What’s remarkable about Avengers: Age of Ultron is how Joss Whedon seems to have learned from some of the issues that plagued The Avengers as a film. The previous film wasn’t his first, but it was a project of a much bigger scale than his previous works, and The Avengers was occasionally shot in a way that showed Whedon didn’t have the firmest grasp on conveying mammoth action sequences. That’s not a problem here. The action sequences are far more fluid, and even though they are notably larger than pretty much any sequence in The Avengers (and there are more of them), Whedon keeps each scene both coherent and visceral. There’s also a notable amount of attention paid to keeping civilians out of harm’s way as much as possible; a large portion of the final act focuses exactly on this.

That personal touch is what’s made Whedon the right choice to corral the various characters of the Marvel Cinematic Universe for these collaborative films. In spite of a story that verges on being overstuffed, each character gets time to shine. Most notably, Hawkeye (Jeremy Renner) – the Avenger most neglected in The Avengers – emerges as the heart of the team, while Black Widow (Scarlett Johansson) and Hulk have a romance that hasn’t been hinted at outside of this film, but feels surprisingly organic. The film also has plenty of moments where we get to watch the team simply hang out, including a memorable sequence where everyone attempts to lift Thor’s hammer.

That doesn’t mean that everything works. In his effort to create as many character moments as the film almost requires, Whedon occasionally eliminates a bit too much exposition; while nothing is exactly incoherent, some of the film’s developments are noticeably underdeveloped. But Whedon’s focus on the characters as being human, with flaws that threaten their ability to use their powers effectively, make Avengers: Age of Ultron an extremely satisfying and exciting superhero film. That opening may make being part of a superhero team, but as the rest of the film demonstrates, it takes a lot of work to make a team like the Avengers work.

Avengers: Age of Ultron • Rating: PG-13 (for intense sequences of sci-fi action, violence and destruction, and for some suggestive comments) • Runtime: 141 minutes • Genres: Drama, Science Fiction • Cast: Robert Downey Jr., Chris Hemsworth, Mark Ruffalo, Chris Evans, Scarlett Johansson, Jeremy Renner, Elizabeth Olsen, Aaron Taylor-Johnson, Paul Bettany, Cobie Smulders, Don Cheadle, James Spader, Samuel L. Jackson • Director: Joss Whedon • Writer: Joss Whedon • Distributors: Marvel, Disney