The Avengers are preparing to assemble once more, and actress Scarlet Johansson promises that the superhero collectives' second outing will be darker than before.

With filming for The Avengers: Age of Ultron is set to begin early this year, cast members have already become acquainted with their new scripts and have begun to give fans a clearer picture of what's in store for Nick Fury's (Samuel L. Jackson) team in the Joss Whedon film.

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"I think the script is dark and it's dry, it's got this amazing one-liner, glass-cutting sense of humour," Johansson, who is returning to her role as Black Widow, told Parade magazine (via the Mirror). "Obviously the script is very cerebral. It doesn't lose that exciting comic book aspect that people enjoyed in the first film, but it's smart and it feels like the next installment."

While Age of Ultron will feature all of original 2012 Avengers team, Whedon has added in several new characters. Quicksilver (Aaron Taylor-Johnson) and Scarlet Witch (Elizabeth Olsen) will feature alongside Iron Man (Robert Downey Jr.), The Hulk (Mark Ruffalo), Captain America (Chris Evans), Hawkeye (Jeremy Renner), and Thor (Chris Hemsworth).

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"It doesn't feel like a rehashing, it feels like these characters are moving forward, plotlines are moving forward," Johansson said of the Avengers cast, according to Parade. "It's deep and I think that's why people really respond to the Marvel universe, because the films are fun and exciting and have all that flashy stuff, but there's a gravity to them. People can expect that gravity this time around."

The Avengers: Age of Ultron will hit theaters on May 1, 2015.