There's something big happening in the sewers of New York City. Nickelodeon has announced the cast of Rise of the Teenage Mutant Ninja Turtles--the newest reimagining of the Teenage Mutant Ninja Turtles animated series--and there are some significant changes coming.

Rise of the Teenage Mutant Ninja Turtles taps into the mystic side of the story about four mutated turtles--Leonardo, Donatello, Michelangelo, and Raphael--who are raised as brothers by their mentor and sensei Splinter, a mutated rat. An official description from Nickelodeon says the series "follows the band of brothers as they encounter new allies and villains and discover a mystical world they never knew existed beneath the streets of New York City."

With the new story comes a new cast. Ben Schwartz (DuckTales) will voice Leonardo, described as "the self-professed 'coolest' brother possesses irreverent charm and a rebel heart." One word missing from that description to longtime turtle fans is "leader." Instead, that role falls on Raphael, voiced by Omar Miller (Ballers).

The turtle with a red bandana "is now the leader and his enthusiasm and bravado puts him front and center for most of their bizarre adventures." Michelangelo, who is "an artist and awesome skateboarder with a wild, colorful, and imaginative personality," will be voiced by Brandon Mychal Smith (You're The Worst). Finally, Josh Brener (Silicon Valley), will portray Donatello as "an unflappable mechanical genius and tech wizard whose ninja skills are second only to his coding."

While the changes in hierarchy within the Turtles will put an interesting new spin on the group dynamics within the show, the most notable change comes from the group's human friend, April O'Neil. Describing April as "a street savvy native New Yorker who is always ready to join in the fun," Rise of the Teenage Mutant Ninja Turtles will be the first time in the franchise the character is portrayed as an African-American woman. The Vampire Diaries alum Kat Graham will voice the role.

Character art will debut before the end of the year, with the series premiering in 2018. The initial season will consist of 26 episodes, airing on Nickelodeon.