Legion of Super Heroes courtesy of Warner Bros. Animation Legion of Super Heroes courtesy of Warner Bros. Animation

The second season of the animated series Legion of Super Heroes premieres tomorrow (Saturdays, 11 am/ET, The CW), but don't expect it to look much like the first. Picking up several years later, Superman is a little bit older and has definitely started to fill out his spandex. "This is more of a classic Superman," says producer James Tucker. "He's not going to be the scrawny kid from the first season."

The basic format of the series, which is based on DC Comics characters, is still the same: The young Man of Steel is once again plucked from the present day by the Legion a fledgling group of young crime-fighters from the 31st Century to add muscle to their intergalactic squad.

This season's big villain is Imperiex, a 41st Century "techno barbarian with aspirations to be a world conqueror," according to Tucker. A Superman clone from the future recruits Superman and the Legion to take him on. This clone, "is not a hero at heart," Tucker says. "He was bred to fight Through the course of the season the Legion is going to teach him how to be a true hero."

While this is still a Saturday-morning 'toon, it's definitely not as happy-go-lucky as the first season. "This is going to be a lot darker tonally," Tucker admits. "It will still appeal to kids, but the stories will be a lot more complex than the first season." - Reporting by Rich Sands