"Yes…yes…yes! New high score!" exclaimed the Doctor, holding up Amy's iPhone in triumph. Amy and Rory did a victory dance around him, but the celebrating was interrupted.

"Hello, Doctor," said the Master, smoothly barging into the TARDIS.

Amy and Rory gasped. "Who is that, Doctor?" asked Amy.

"Isn't that that Harold Saxon bloke? The one who ran for Prime Minister and then went buggy?" added Rory.

"Well, yes, but his name isn't really Harold Saxon," said the Doctor. "He's really a Time Lord, like me. His name is the Master."

"I like it when you say my name," said the Master, smirking.

"Yes, I know you do," said the Doctor exasperatedly. "What are you even doing here, anyway? I thought you got sucked back into the Time Lock."

"Well, I managed to get myself out. Just to see what my most dastardly adversary is up to, and how I can ruin your plans."

"We're not really doing anything right now," said the Doctor. "So, you can just go now…"

"Nothing? Really?" The Master raised a suspicious eyebrow. "I find that hard to believe."

"All we're doing is playing Flappy Bird," said Amy.

"'Flappy Bird'?" repeated the Master. "What is this 'Flappy Bird'?"

"It's a video game," said Amy, showing the Master her phone.

"The Doctor's just beaten Amy's high score," added Rory.

The Master looked down at the screen. "Twelve?" he said incredulously.

"Yeah, I know," said the Doctor, proudly straightening his bowtie. "Pretty cool, right?"

"This is but a pitiful little human game," laughed the Master. "Why, I could beat your silly little score like that," he said, snapping his fingers.

"Oh really?"

"Yes, really."

"Okay then. You're on," said the Doctor. "Care to make it a bet?"

"Of course! You know I love a good wager," said the Master.

"Alright. If you can't beat my high score, you have to go back to the Time Lock," said the Doctor.

"Fine," agreed the Master. "But if I win…I get your TARDIS." He smiled evilly.

"Then it's settled. And may the best man win," said the Doctor, shaking the Master's hand.

"Oh, I intend to." The Master hit the play button and began tapping.

"Doctor! What are you doing?" gasped Amy. "What if he beats your high score?"

The Doctor smiled knowingly. "Trust me. I'm the Doctor."

"Darn!" The Master had just lost. "Well…fine then. I just have to get the hang of it, that's all."

Ten tries later, he still hadn't gotten it.

Twenty tries later, he still hadn't gotten it.

Fifty tries later, he still hadn't gotten it.

"Alright, Master, you've made a valiant effort," said the Doctor. "Don't you think it's time to quit now?"

"NO!" shouted the Master, staring fixatedly at the screen. "I must beat your high score! I must defeat you, Doctor!"

"But the farthest you've gotten so far is two," Rory pointed out.

"That's about to chan-NOOOO!" he howled as he lost again, and restarted the game.

Amy watched the Master tap the screen furiously. She was starting to worry that he would break her phone…wait. Then she noticed it.

The Master's tapping. It was weird. It was always in a steady sequence of four. One, two, three, four. One, two, three, four. One, two, three, four. It seemed like an odd strategy to Amy.

Finally, after exactly 6,502 attempts, the Master admitted defeat. Tail between his legs, the Master was returned to the Time Lock.

"You see, Amy?" said the Doctor, shutting the doors behind his arch nemesis. "I knew he couldn't beat my high score."

"Why did he tap with that weird one-two-three-four rhythm?" asked Amy. "It was throwing off his whole game."

The Doctor smiled smugly. "I know."

"So in other words, you cheated," said Rory.

The Doctor shrugged. "Cheated, made use of prior information. Whatever. Now, anyone fancy a trip to Rio?"