Michelangelo paused on the ladder into the sewer and looked up at the oversized form of Tokka. He couldn't resist. He reached up and tickled Tokka's feet. Tokka kicked and giggled. It was pretty weird.

"Come on," Leonardo said. "We've got to meet back up with Splinter."

But first, there was the professor. He stared at the foursome. "Four turtles!" he said, as if he'd just realized who had rescued him.

"Yeah, the guy's Ph.D. material all right," Raph joked.

"And so intelligent! It's incredible," Professor Perry said.

"Hey, don't freak, dude, we can explain," Mike said. "See..."

The professor began speaking then. It was as if he knew what Mike was going to say. "Fifteen years ago, you came in contact with a green colloidal gel down in a sewer that transformed you into your present state."

The Turtles stared at him in disbelief.

"Fascinating," the professor said.

The Turtles thought it was definitely fascinating. There was a lot to talk about, but it would have to wait until they got back to their new home. Just to be on the safe side, they blindfolded the professor. They didn't want anybody to know the whereabouts of their den.

When the blindfold came off, the professor looked around at the reconstructed underground station.

"Ingenious," the professor said.

"We'll give you the tour later," Leo told him. "Right now we've got a few questions."

Splinter stepped out of the shadow. The professor's jaw dropped when he saw the rat. Splinter spoke then, "The professor has much to tell us."

It was true, too.

Once introductions had been made, the professor began talking. He explained about an experiment TGRI had been conducting fifteen years before.

"...Of course, laboratories were crude back then and an accident was just waiting to happen."

"You mean to tell us that the formation of the ooze was all just a big mistake?" Don asked. He didn't like that idea. He preferred to think that he and his brothers had been planned.

"Well, you see, Donatello, an unknown mixture of discarded chemicals was accidentally exposed to a series of radiative waves. The resulting, uh, ooze, as you call it, was found to have remarkable and dangerous mutagenic properties."

"Huh?" Mike asked, looking to Raph for an explanation.

"Big mistake," Raph translated.

"Well, on our way to bury it, a near-collision caused us to lose one of the canisters down a sewer. Fifteen years ago."

That was the answer. Now the Turtles and Splinter knew the real answer to their existence. They were just one big mistake on top of another.

The professor excused himself then. He needed a rest. The Turtles needed a rest, too. They were all feeling let down.

"What troubles you, my son?" Splinter asked Don, who seemed particularly low.

"I don't know," he said. "I just always thought there'd be more to it. I thought we'd find out we were special."

"Do not confuse the spectre of your origin with your present worth, my son. The search for a beginning rarely has an easy end. For now, though, our search will have to wait. Tonight's encounter has left us with larger problems."

There were names for those problems: Rahzar and Tokka.