Los Angeles, Jan 27 (IANS): Actress Naomi Watts is guarded about the plot of the "Game of Thrones" prequel, but says it is going to be very exciting.

Watts, who was at the Sundance Film Festival for her film "Luce", stayed mum on all things "Game of Thrones", reported variety.com.

"Do you really think I'm going to tell you that? Are you trying to catch me off guard," Watts asked with a laugh.

Nevertheless, expressing joy about being a part of it, she said: "It's a fantastic world, isn't it? I think there's so many brilliant elements to that series that make it very exciting, very appealing. I don't want to dig myself into a big hole here... All I want to say is it's very exciting…I'll say that again and again and again - and nothing else."

Asked if she knows how the flagship "Game of Thrones" will end, she laughed again, and said: "Stop please! I can't. I just can't."

Then, her "Luce" co-star, Octavia Spencer, chimed in from off-camera, joking that she wanted to get some spoilers: "I'm going to talk to her about this off screen!"

In "Game of Thrones" fashion, HBO has kept the exact details of the prequel and Watts' character under wraps, though the network has described her character as "a charismatic socialite hiding a dark secret".

The prequel hails from Jane Goldman who co-created the project with "Game of Thrones" master author George R.R. Martin. The duo wrote the story together and will both serve as executive producers. Goldman will serve as showrunner, and other executive producers are Daniel Zelman, James Farrell, Jim Danger Gray, Vince Gerardis with Chris Symes as co-executive producer, reported variety.com.