"Oh." Right, she forgot some people weren't as familiar with the TARDIS, even in Madison Valley. Martha patted the side of the blue box fondly. "This is actually a TARDIS, not a police box. It's like- " She made a vague gesture with her hand as she tried to find the right words. "A space ship and a time travel machine all wrapped into one. And it's bigger on the inside than the outside. Dimension manipulation."