So the Doctor and Kayla continued strolling through the park she appeared in, while the Doctor explained to her everything about space and time. When he finished, they had arrived at the Tardis.
"So this is a space time machine?" asked Kayla.
"Yup," replied the Doctor
The Doctor unlocks the Tardis slowly to build up anticipation. When Kayla walks into the Tardis she is struck with by a pure sense awe. Then she runs back outside, runs back inside, then back outside again. She circles the Tardis and walks back in. "It's bigger on the inside!"
"Yeah I get that a lot. It's because it's a space time machine," reply's the doctor.
"Hunh makes sense."
Just then a massive earthquake happens and the Doctor runs outside. He gets outside, looks around, and starts running towards a very large building. Kayla, not wanting to miss out and lose the only way back to her old life, follows after him screaming for him to wait up