Diane Lane on 'Superman' Secrecy: 'I Had to Read the Script Under Lock and Key' (Video)

Diane Lane, who is set to play Clark Kent's adoptive mother in the upcoming Superman: Man of Steel, addressed the huge amount of secrecy surrounding the script.

"I'm not allowed to talk about it. It's top secret," she said Wednesday on NBC's The Tonight Show With Jay Leno of her role as Martha Kent.

In fact, Lane was essentially sequestered when she first read the script.

"Of course, there is a lot of secrecy these days, with the Internet and everything, and rumors get started, so I had to read the script under lock and key in a room. You go to the offices, and it's a locked door and the curtains are drawn, and so, that was the time I had."

Lane also expressed amazement that she is part of a potentially blockbuster film.

"I'm going to be in one of those huge movies," she said. "I can't wait to see it already. I'm kind of amazed.

Henry Cavill also stars as the title character, with Kevin Costner as his adoptive father, Jonathan Kent.