One year after stopping Shredder, the Teenage Mutant Ninja Turtles are informed by April O’Neil that scientist Baxter Stockman is working for Shredder and plans to bust him out of prison. As the Shredder is transferred between prisons alongside Bebop and Rocksteady by corrections officer Casey Jones, the Foot Clan attack their convoy. Despite the turtles’ interference, Shredder escapes when Stockman uses a teleportation device. Shredder is hijacked mid-teleport, winds up in another dimension, and meets the alien warlord Krang, who reveals his plans to invade Earth. He gives Shredder a mutagenic compound in exchange for finding three components of a machine that Krang sent to Earth long ago which will open a portal to his dimension when united, as Shredder and Stockman have the first piece. Casey tells NYPD chief Rebecca Vincent what happened to Shredder, but is met with disbelief, and decides to go on his own.Teenage Mutant Ninja Turtles: Out of the Shadows 2016.
Shredder recruits Bebop and Rocksteady, and Stockman uses Krang’s mutagen to transform them into a humanoid warthog and rhinoceros, respectively. April witnesses their transformation and steals the remaining mutagen vial from the TCRI lab. Pursued by the Foot, she is rescued by Casey, who later meets the turtles, but the vial is taken into police custody. In the lair, Donatello deduces that the mutagen could be used to turn the turtles into humans, but Leonardo refuses and orders Donatello to keep it a secret from the others. However, Michelangelo overhears and tells Raphael, which enrages Raphael and leads to a fierce argument between him and Leo. Raphael then recruits Mikey, April, Casey, and Vern Fenwick to break into the NYPD headquarters and retrieve the mutagen, but the Foot arrive ahead of them. In the ensuing battle, the turtles’ existence is revealed to the police, who start a manhunt for them, and April and Casey are arrested while helping the brothers escape with the mutagen.