'Captain America: The Winter Soldier' Trailer: The Falcon and Bionic Winter Soldier Revealed

The "Captain America: The Winter Soldier" trailer was released Thursday, and fans are excited about the sequel to the first movie in the Avengers universe. In the film, Steve Rogers along with various other S.H.I.E.L.D. agents work to stop a nefarious plot in Washington, D.C. and come up against the Winter Soldier, who turns out to be an old friend of Captain America.

The "Captain America: The Winter Soldier" trailer reintroduces Captain America (Chris Evans) as an agent of S.H.I.E.L.D. after the incident with the Avengers and Loki in New York. He works alongside Black Widow (Scarlett Johansson), but doesn't always agree with the agency's methods, which aren't always 100 percent pure.

"We're gonna neutralize a lot of threats before they even happen," Nick Fury, played by Samuel. L. Jackson, says.

"Thought the punishment usually came after the crime," replies Captain America.

"S.H.I.E.L.D. takes the world as it is, not as we'd like it to be," Fury says.

"This isn't freedom. This is fear," Captain America says.

New characters are also brought into the Captain America universe. Falcon (Anthony Mackie) is Marvel's first black superhero who flies and can telepathically communicate with birds; Sharon Carter (Emily VanCamp) doubles as Agent 13, Captain America's love interest with a secret; and Alexander Pierce is one of S.H.I.E.L.D.'s senior leaders.

"To build a better world sometimes means tearing the old one down. And that makes enemies," Pierce says during the trailer.

The plot gets more complicated with the appearance of the Winter Soldier, who is genetically enhanced to rival Captain America's superhuman abilities and even surpass them with his bionic arm. The assassin is James "Bucky" Barnes," Steve Rogers' close friend from World War II who died in the first Captain America movie.

The trailer has garnered a lot of popularity following its release, racking up 4.2 million YouTube hits in less than a day. "Captain America: The Winter Soldier" is scheduled to be released April 4, 2014 in 2D and 3-D.