Diane Lane lips are sealed about Superman script!

Diane Lane has to keep her mouth shut!

The actress who will play Clark Kent’s mom in the upcoming Superman reboot says details of the script are so top secret that she was only allowed to read it once.

“I read the script under lock and key,” Lane said. “I was locked in a room with the script and was only allowed three hours with it.

“I nailed it into my memory. I’m really excited. I’m really not allowed to talk much about it, I think, but it does cover the entire range of years, from infancy on.”

Lane will star alongside Henry Cavill, who will take on the title character, Amy Adams as Lois Lane, and Kevin Costner as Clark Kent’s father.

The movie  is set for a release in December 2012.

Diane who raises 17-year-old daughter Eleanor with husband Josh Brolin recently insisted that “willing to be wrong” makes her marriage work.

“It’s staying grateful, humble, willing to be wrong and thinking about the other person at least as much as you think about yourself,” she said.

“Put yourself in the other person’s moccasins, you know?”