Speaking about the fourth Bourne instalment, the actress called her character "a nice, normal, regular person" who is thrown into a life-or-death situation alongside new franchise protagonist Aaron Cross (Jeremy Renner).
"The tone is very realistic," Weisz told Vogue magazine. "I'm not playing a superhero, I don't have superpowers. I don't even have a gun. That's really what I love about it, that as this type of film goes it's not implausible at all."
She went on to reveal that Matt Damon's Jason Bourne is "in the periphery" of the story, but not centrally involved.
"It's about a new military programme, and I am thrown together with Jeremy Renner's character by circumstance, because, well, we need each other," she explained.
Damon has said that he "expects to return" to the Bourne franchise in the future, while Renner has expressed a desire to collaborate with Damon on the next instalment.
The Bourne Legacy is released on August 3 in the US and August 13 in the UK. Watch the trailer below: