‘Captain America’ Trailer: Steve Rogers, Frustrated Agent of S.H.I.E.L.D.

World War II and the threat of HYDRA seem like simple challenges compared to the morally compromised modern world on display in the first trailer for "Captain America: The Winter Soldier," next spring's Marvel movie that puts the red, white and blue hero front and center.

Except the red, white and blue has faded a bit — not just in Cap's sleeker, sexier and inevitably darker costume but in the America he has sworn to protect, one where "disorder and war" is just one step away. Back in WWII, there were the 'good guys' and the 'bad guys'; today, the defenders of the country, particularly the agents of S.H.I.E.L.D., seem to follow a more complicated and perhaps corrupt code of ethics, one enforced by Alexander Pierce (Robert Redford, perhaps playing an upgraded variation on his "Spy Game" character).

"To build a better world sometimes means turning the old one down ... and that makes enemies," says Pierce to the troubled Steve Rogers, who now officially joins the ever-growing ranks of haunted and deeply conflicted superheroes in this entry.

What's more sinister is Rogers clashing with his superior officer, Nick Fury (Samuel L. Jackson). Jackson's got the crazy eye (emphasis on just the one eye) as he targets his trademark Sam Jackson glare in Cap's direction, delivering pop comic book philosophy such as "S.H.I.E.L.D. protects the world as it is, not as we'd like it to be" as if it were a grave threat. Later, we hear Fury warn Cap, "You need to keep both eyes open" (haha), hinting that the S.H.I.E.L.D. bigwig might actually be something of an antagonist in this one — and one who gets seriously hurt as the vehicle he's driving gets blown onto its back later on.

The trailer's not all doom and gloom, though: This is a Marvel movie, after all, and it's the sense of humor in the face of danger that often makes these comic book adventures even more thrilling. Black Widow (Scarlett Johansson) is in the background for most of the trailer, though she does open it with some witty Joss Whedon-ish banter about dating, with Cap claiming his Saturday night is open because "all the members of my barbershop quartet are dead." Cap also gets a particularly badass moment when he takes out an elevator full of what appear to be a bunch of S.H.I.E.L.D. suits in about two seconds flat.

However, the real fan service happens in the last 30 seconds of the trailer, where we get a look at the film's main heavy, the Winter Soldier. The villain's identity (he's Cap's old war buddy Bucky Barnes) isn't revealed, nor does he even speak — all that's needed to show that this guy is going to be a major problem is his ability to grab Cap's shield with his bare hand after it's thrown at his head. For now, the Winter Soldier comes across as a more lithe and athletic Bane from "The Dark Knight Rises" — a masked force of nature, though one who can run and leap a bit more than his burlier Gotham counterpart.

And what's a big tentpole movie without some giant flying object engaging in a crash-landing? We saw it this summer in "Star Trek Into Darkness"; here we see what looks like a S.H.I.E.L.D. Helicarrier taking a fiery nosedive.

And yeah, we get to see Falcom (Anthony Mackie) fly. It's now no wonder why Mackie was geeking out about his role so much at the "Captain America" press conference at this summer's San Diego Comic-Con — it's a pretty cool sight.

Ultimately it's great to see Steve Rogers in a dark, serious-minded political thriller that questions his own alter-ego identity and asks what, indeed, is a 'Captain America' of the 21st century. However Rogers comes to terms with this, it makes for a huge task and great responsibility: "You've shaped a century — I need you to do it one more time," says Pierce. It's not every S.H.I.E.L.D. operative who gets an assignment like that.

"Captain America: The Winter Soldier" opens April 4, 2014.