Oh! Sorry, Mask, I forgot you asked for that... do you still need a recap?
EDIT: Ah, I just did it anyway. *shrug*
Leatherhead freaks, and falls on his knees on the floor, Donnie is gonna attack him, when he gets hit with a tranquilizer dart. The next shot reveals that Leo was the one who tranked him. "Donnie, I'm sorry, but this is for your own good." Don comes *growl snarl* down the catwalk at Leo, who walks slowly toward him, steadily shooting tranquilizers (and looking like he's really steeled himself to do this, it's hard for him), until, after eight more (!), poor Don finally gets sluggish and collapses. Leo crouches at his side, rubs his shell, "It's gonna be all right, Donnie". (blub!

)
Next scene has Donnie floating in a containment unit. Baxter says: "Hmm. Donatello's body appears to be breaking down at a fantastic rate, due to secondary stage mutations caused by the outbreak accelerant. He doesn't have much time. The animal was right," he adds, snidely, referring, I think, to Leatherhead, who growls at him, not amused. Leatherhead says, "Leonardo, this is wrong. We cannot leave Donatello's fate to these devils. Stockman cannot be trusted. And him!" he indicates Bishop, "if you only knew what he was capable of!" His eyes change. He's not a happy croc.
Raph chimes in. "Leatherhead's right, Leo! Bishop's the enemy! He's the one that caused the outbreak in the first place!"
Bishop says, "Stockman created the genetic accelerant on my orders. What you call the 'outbreak virus' is an unintended side-effect of... one of my operations."
Leo says, "Do you have a cure?"
Silence. Bishop looks at the guys. The guys look at Bishop. Bishop subtly looks at Baxter. Baxter shakes his head minutely. Bishop looks back at the guys. "Yes," he lies, with a smug smile (hisssss!). "But as I said earlier, I need something from you." The guys exchange narrow-eyed glances, and Leo says, "Name it."
"A simple errand, really. There is an item I require. A relic, that may prove crucial to my work. I want you to retrieve it for me."
"Retrieve it? From where?"
"New York. In fact, I believe you know the woman who currently holds it. Her name is... Karai."
Everyone goes, gasp! The end.
