Edit: Whew! Didn't know this would be this long until I posted it! Kudo's for anyone that reads it
Shredder recovers from his fall and uses a tiny bit of the mutagen to heal himself of his various injuries. He goes back to Sack's lab and brings with him Baxter Stockman, telling him and Stockman that they better work on creating more mutagen 'or else' because he wants his own mutants to better fight those 'freaks.'
Well, meanwhile April is trying to get her job back. Hanging with 4 Turtles doesn't pay the bills while living in NYC, so Bernadette decides to give her another chance just this once, mainly because she is down one or two reporters and needs someone to cover the feel good 'fluff' stories for the time being.
While traveling to one of her assigned stories, April notices something suspicious. Pulling over, she's shocked to see that it's more of the Foot, and these catch sight of her and capture her. Before she is captured, she uses the Turtlephone to try and call one of the Turtles, however she hits Vernon's number by mistake, and gets him. She still begs him to get help from the Turtles, but him wanting to be a tough guy, decides to try and rescue April himself. He uses the phone's GPS to track her last signal, and arrives at the place she's at (an abandoned warehouse.) He gets captured and tied up,and taken to Sack's and Baxter's lab along with her.
Shredder comes into the lab. He gloats that if she she is going to be Turtlebait to bring the Turtles, but because her meddling brought about so much trouble, he's going to add in a punishment. Not for her, but for her boyfriend Vernon, and she's going to watch him carry it out. April screams 'No,' and Vernon tells her, 'No matter what happens, I'll always love you."
Shredder orders Sachs and Stockman to hook Vernon up to some device with tubes, where they proceed to pump mutagen into Vernon's body, with Baxter injecting a vial of Rhino DNA into Vernon's veins. Vernon mutates, while April screams.
Meanwhile, Shredder uses the captured Turtlephone to call up one of the Turtles. He mentions that he's captured April, and that they better come before his freaks kill her.
In the background, Baxter mumbles to Sacks, 'Freaks? What freaks? We only made one." Suddenly Sacks pulls out a gun and points at him, saying, "Well, you are going to be freak number two. You are an expendable asset right now, and you know too much. Get in the other chair." Baxter is frightened, and complies by sitting in the other chair.
Sacks' ties him up, and hooks more tubes into him. He injects Warthog/Wild Boar (I can't decide which) into Baxter's arm and turns on the mutagen pumps. Baxter is screaming, while Vernon is already making rhino-like noises (whatever those sound like.)
Meanwhile, the Turtles are rushing to get to April. Mikey is having one of his moments and is exclaiming 'My precious April!" while Raph tells him to shut up. They are driving through traffic and one of the van's tires gets popped by a pot hole, forcing them to get out and travel by rooftop. Mikey complains 'Awe, we gotta walk?" while Raph deadpans a 'Well, maybe it will burn some of that pizza off your butt." Donna mentions something about triangulating Aprils' coordinates and Leo talks about making sure nobody sees them and needing to trying to find the fastest route possible to get there. Donnie suggests riding atop a train, and Leo agrees. They hop down a manhole,and find their way to a station. They all jump onto the roof of a train that Donnie says is going in that general direction, and they hop on.
Back at Sacks' lab, both men have finished mutating. They straining in their restraints, and both are making animal like noises. April has tears in her eyes, and mouthing "Vernon, Vernon..."
The Turtles' train carries them close enough, but after they jump off Donnie says that traveling on foot will still take a while for them to get there. They find a parked truck in the shadows, and Donnie breaks into it and hot wires it. Two Turtles sit in the front and two hunched down in the truck bed, and they drive the rest of the way to Sack's lab. They encounter some Foot, but their bullets don't affect the Turtles.
The Turtles burst into the lab, and Vernon and Baxter become excited and break from their restraints. The Turtles and the new mutants fight, but the new mutants end up proving to be a match for them. Mikey quips that they guys like to hit hard, and that he can't land a hit on them, and during this, one of them ends up knocking him and Donnie against the wall. They land against a wall, and Mikey quips 'We're getting tenderized dude! We gotta do something!"
*Meanwhile in the background, Shredder quietly leaves*
Well, Donnies notices that where they land is some power cables, and this gives him the germ of an idea. Looking quickly, he notices some sprinklers on the ceiling, and a plan now fully forms. He yells, "Guys, get to someplace non-conducting quickly!" The other three look at him for a moment, and then quickly scramble for anything non metal to stand on. Mikey grabs April and goes for a pile of rubber mats, Raph, goes for a stack of wooden pallets, and Leo goes for a sturdy desk. Donnie jumps up, and whips out a cigarette lighter as he gets a hold of a beam, and lights it under a sprinkler head. The sprinklers activate, and Donnie yells, 'Guys, cut open those power cords!" The guys all throw their shuriken at it, and the power cords start to spark in the water. Vernon and Baxter are caught in the electrical discharge, and are electrocuted to death.
Soon the power stops, and Donnie determines that it's safe to step down now because a fuse blew and cut the electricity. They free April and she's crying, and runs over to Vernon. He's clearly dead, and the Turtles decide they better get leaving and not risk sticking around.
Donnie decides hot wires a Clan Humvee, because there isn't enough room with April now. Two Turtles ride in the Humvee and two are in the truck, and Mikey is consoling April. In the background of the lab, there is another Foot soldier watching them through a window as they are leaving. He tears off his mask, although we only see him from the back. He turns, and the screen fades to black. *It turns out to be Casey Jones*