Since “Iron Man” was released in 2008, Marvel Studios has been slowly filling a world with characters, building the foundation for next summer’s “The Avengers.” With “Captain America: The First Avenger,” the last of the building blocks falls in place, and thankfully Marvel has saved their best film for last. “Captain America” is not only one of the best films of the summer, but it’s a benchmark for the superhero genre as a whole.

Chris Evans stars as Steve Rogers, a scrawny runt of a boy who wants nothing more than to join the Army and join his countrymen in fighting World War II. Rejected time and time again, Steve keeps coming back until Dr. Abraham Erskine (Stanley Tucci) offers to make him the first in a line of scientifically enhanced super soldiers.

Evans shines in these early scenes as the barely-there Steve, giving the character a heart and inherent decency that informs the entire film. He’s even better once Steve becomes Captain America, dominating the screen with magnetic charisma befitting a superhero.

Stanley Tucci leads an impressive supporting cast. His Erskine veers between a hammy German accent and a scientist genuinely passionate about his work, but Tucci’s gentle, controlled performance makes the character work. Meanwhile, Tommy Lee Jones scores some unexpected laughs as a hard-headed Colonel, and Hayley Atwell shines as the radiant Peggy Carter, Steve’s love interest. This is one of the rare superhero romances that doesn’t feel forced, thanks in equal part to Peggy’s smart, three-dimensional characterization, no shortage of chemistry between Atwell and Evans, and an ending that’s decidedly unhappy. The surprising left turn for a superhero film was nonetheless necessary to get everyone into place for “The Avengers.”

Above all, “Captain America” feels like a classic action-adventure film. Many scenes could easily have ended up in a Bond or Indiana Jones film and not felt out of place, mostly thanks to director Joe Johnston, who has been making these adventurous, easily entertaining popcorn films for two decades. Johnston stages every action scene with enthusiastic vigor, but he also makes the slower expository scenes crackle with energy as well. He sells Steve Rogers’ transformation into a true American hero without making him overpowered or unlikable.

If there’s one thing truly wrong with “Captain America,” it’s the film’s brevity. With such a massive supporting cast, several characters get shorted. In addition to the characters already mentioned, there’s also the film’s villains, played by Hugo Weaving and Toby Jones, and an entire team of characters who back Captain America on the battlefield. The film takes place over several years, and Johnston paces things well enough that it never feels episodic, but an extra 20 minutes or so could have done wonders to add some detail to the world and characters.

Unfortunately, “Captain America” also ends with little chance of having sequels set in the World War II environment the character is created in, which is quite a shame. However, it’s a film that doesn’t really need a sequel — a truly entertaining superhero film that tells a commonplace origin story with enough flair. The film never feels like something you’ve seen before, and it’s an excellent primer for next summer’s “Avengers.” If the quality seen here and in some of the other Marvel Studios films carries over into that film, we’re certainly in for a treat next summer.