"Alright," said the Doctor, holding out his hands for everybody to remain calm, "Nobody move. Cassandra could be anybody in this room."

However, the glee kids were looking around at each other still, untrusting and unwilling to listen. (Each one didn't quite believe what was going on, but they all decided that, if they didn't believe in aliens by now, the story would probably take a turn for the worst. So they sucked it up and decided to be reasonable.)

"Doctor," said Amy, creeping out from behind the TARDIS with Rory, "How can we tell who she is?"

"We can't."

"Well, she can't be a bloke… can she?" asked Rory.

"Yes, she can," he replied, looking closely at every person in the room. (More than one recoiled at his weirdness.)

"Well, Mr. Know-It-All," called Mercedes, "How do we know that Cassandra isn't inside of you?"

The Doctor sighed. "Really? You're really going to accuse me?" He muttered almost to himself, "Why do humans always go around doing that?"

Mercedes stood up, hands on hips, and said, "Humans? Oh, no way are you calling us just 'humans,' and –"

Then, Artie cut her off. "Wait, a minute. Why would Mercedes say 'no way?' She always says," He imitated her voice with spooky accuracy, "'Hell to the NAW.'"

"You're right," added Quinn.

"That is not Mercades!" cried Tina.

Mercedes looked mad for a moment, then slumped back into her seat. "Oh, alright then," she said in a very authentic British accent. "I'll just have to try harder next time."

Mercedes leaned her head back, and a loud scream echoes through the room, as a red light emanated from her mouth. The light grew brighter and bright, until it was too bright for anyone to see. Then it withdrew, and Mercedes shuddered and rubbed her head.

"Woah…" she said. "That was weird."

"Alright!" said the Doctor rushing up to Mercedes and propelling her towards the TARDIS, "Into the box you go."

"But… What happened?" she stammered.

"No time to lose. Whoever we know is not inhabited goes into the TARDIS, so we can keep track and identify Cassandra better." He shoved the protesting Mercedes into the box, then locked the door, ignoring her shouts of both awe and anger.

"So," said Amy, "We're back to square one?"

"Basically… yeah," he replied.

"Listen, sir," Mr. Shuester couldn't bring himself to call him 'Doctor,' "But how are we going to get the kids… safe?"

"Process of elimination," the Doctor replied. "we just have to narrow it down, then, I can solidify Cassandra's consciousness and contain it."

"We'll need to ask them all questions," Will replied, "Questions only the real person would know the answer."

"Right," said the Doctor, "Let's go into the office to plan out what we'll say. We'll interrogate them each separately. Mr. and Mrs. Pond! Come with us." The four adults then went into the adjacent room, and the glee club talked freely.

"I saw that," said Lauren to Puck.

"Saw what?" he said incredulously.

"When he said 'Mrs.' You looked disappointed. You don't like the fact that that Amy lady is married."

Puck rolled his eyes. But he was disappointed, only in the sense that it would be harder to get into the ginger's pants. Harder, but not impossible.

"I don't know what you mean," he said, and turned away. But secretly, he was imagining Amy Pond-Williams in her underwear, because that's just what Puck does sometimes.