"So, you can't fix it, then," Clara said.
"What?" said the Doctor. "Of course I can. I can fix it any time I like."
"Right. So go ahead, then."
Clara, her arms crossed, was standing in the TARDIS control room on the opposite side of the console from the Doctor.
The Doctor frowned. "I'm busy," he said, and began flipping switches with a flourish and darting about the TARDIS console.
Clara raised an eyebrow. "Busy."
"What? Yes, of course I'm busy. I've got..." and the Doctor stopped short, a puzzled expression on his face.
"Switches to flip?" Clara offered.
"Switches to flip," agreed the Doctor. "Very important switches that need flipping."
Clara turned her back to the Doctor. "Can't do it then. So disappointed."
Silence behind her.
Tilting her head back, Clara added the final touch. "Oh, and I used to think he was clever."
"Oh, alright!" said the Doctor.
Clara spun around. "You'll do it?"
The Doctor, wearing his best grumpy face, said, "Yes, I'll do it. Even though I like it the way it is," he added, petulantly.
Removing a panel from a wall of the control room, the Doctor withdrew his sonic, made an adjustment, and activated it. That done, he pocketed the sonic and replaced the panel.
"What, that's it?" said Clara. "Chameleon mechanism broken for hundreds of years and that's all it takes to fix it?"
"I told you," the Doctor said, stepping inches from her face. "I liked it."
"Show me, then." said Clara. "Land somewhere. Show me it works."
Pulling the lever that activated the materialization circuit, the Doctor said, "London. 2013."
After they landed, Clara darted out the door to look back at the TARDIS. The Doctor followed more slowly, closing the door behind him.
It was night, but in the dim light Clara and the Doctor stared at the form in front of them.
"Fixed it then, did you?" Clara asked.
"What? Yes, of course I fixed it."
"So why's it still a police box?"
"Yes, why?" muttered the Doctor, pacing about. "Why is it a police box?"
The TARDIS had materialized on a sidewalk. The street was deserted, cars parked on both sides. No pedestrians, no traffic, it must have been the middle of the night. The shops, butchers, laundrettes, travel agencies, chemists, were all closed up. Then the Doctor laughed out loud and clapped his hands together.
"Because it's not 2013, we must be back in the 50's or 60's. Look at the vehicles."
Clara approached the closest vehicle and realized he must be right. It was an old, green Vauxhall, a big, heavy beast of a car. Next to it was a classic Ford, and so on.
Squinting, the Doctor looked further down the sidewalk, then lit his screwdriver, and strode off in that direction. Clara followed.
"What is it?" she asked. "What do you see? I can hardly make out a thing."
"Look here," he said, triumphantly.
Eyes wide, Clara said, "It's another police box."
"Exactly. They were common in London in the 1950's. So. In the last nanosecond before it materialized, the TARDIS examined its surroundings and selected a form in which it would be inconspicuous: a police box. The chameleon circuit works," the Doctor concluded, flipping his sonic in the air and pocketing it once again.
Moving his face closer to Clara's, the Doctor said, "It's fixed."
But Clara ignored the Doctor, looking about at her surroundings instead.
"Doctor," she said, "something's not right. This is London, yet there's not a sound. No horns, no police sirens, no traffic. And there's not a single light on in any of these buildings. And the street lights aren't working."
"Oi!" said the Doctor, as the street was suddenly flooded with blindingly bright light.
"What on earth?" Clara began, but the Doctor shushed her.
"Listen," he said.
Clara listened and heard a series of loud, echoey thuds.
"Doctor, they're getting closer, whatever they are," she observed.
"Get down," said the Doctor, "behind one of these vehicles."
Crouching low, they waited as the sound changed, from thuds to a softer but still loud padding sound. When the sound stopped, they peeked over the bonnet of the car.
Clara was about to exclaim, but the Doctor covered her mouth.
There was a face hovering over the buildings in front of them. A gigantic face. A boy's face. About ten or eleven, with haphazardly styled hair, in-ear headphones, and eyeglasses that were clearly modern, not the 1950's Buddy Holly style. All perfectly normal, except for the fact he seemed roughly the size of Godzilla.
After a moment, he turned away. Clara and the Doctor heard the same gigantic footsteps as before, then once again they were plunged into darkness.
The Doctor sat down on the curb of the street and let out a long, loud laugh.
"You think that's funny?" Clara asked. "With Godzilla boy stalking through London? Cause for some concern I'd say. And somehow he can control the sunlight, turning it on and off like..."
The Doctor looked up at her.
"Like?" he prompted.
"Like a switch," she said.
"Exactly," said the Doctor, getting to his feet. "Though he's not the size of Godzilla, rather we're the size of mice. We are in 2013, but we landed on a tabletop representation of 1950's London."
"What?" Clara said.
"You wanted proof the chameleon circuit works?" The Doctor spread his hands about him. "Proof. Landing on this tabletop, the chameleon circuit attempted to disguise itself. It couldn't very well do that as a full size police box, so it became a model-sized police box, shrinking us with it."
Clara digested that. "You know, Doctor," said Clara, "I think I liked it better before."
"I couldn't agree more," said the Doctor. "Let's get back and undo that fix, shall we?"