With the recent confirmation of Hayley Atwell's return as Peggy Carter in Captain America: The Winter Soldier, TheAge.com.au spoke with the actress for any details on her upcoming appearance -- but she couldn't say much.

"They're so tight, the Marvel family, and private," Atwell said. "I can say that I am involved in some way in the second [Captain America movie]. Just know that it's not me being cryptic, it's Marvel. They can just as easily kill me off if I threaten to tell the story before it's time. They're keeping it all under wraps."

However, the actress was able to share that Marvel plans to show more of what the character can do with footage to be screened in July at Comic-Con International.

"Marvel have made sure that as part of Comic-Con there will be a little kind of snapshot as to what Peggy's actually really capable of, which was finished here and which was great fun," she said. "Hopefully, it will lead to other things." That of course brings to mind a short film, akin to the "Marvel One-Shot: Item 47" shown last year.

Atwell also indicated her interest in returning to the character again, hopefully in a spinoff set in the modern day -- which may not be out of the question, considering Peggy Carter hasn't yet been seen in the current era.

"I'd revisit Peggy again. She's pretty uptight. I'd like to, if I get a spinoff, definitely add a bit of humour in there,” she said. “She's very British. Very uptight. Let's hope if she gets a spin-off it's modern day, so she can relax a little bit, let go of the uniform."

Until very recently, whether Atwell would reprise her role in Captain America: The Winter Soldier was somewhat of a mystery. In January, she supposedly wasn’t returning for the sequel, but in February, Stanley Tucci said she'd been back in a cameo. The confirmation came with the official synopsis for the film, which listed Atwell as a member of the cast.

Directed by Joe and Anthony Russo, Captain America: The Winter Soldier features Marvel Cinematic Universe alums Chris Evans, Scarlett Johansson, Samuel L. Jackson, Sebastian Stan, Cobie Smulders, Haley Atwell, Toby Jones and Max Hernandez, along with newcomers Anthony Mackie, Emily VanCamp, Frank Grillo, Georges St-Pierre and Robert Redford.