After the day they've had, the Doctor decides, they deserve an afternoon stroll. Donna lets him choose their path, and they walk through the quiet suburban neighborhood in companionable silence.
Two boys, maybe eight years old, plot mischief together; a trick of the wind blows their words to the wanderers. "I dare you to knock-down ginger Mrs. Bucket's house."
"You ever do that where you're from?" Donna asks. "Knock on someone's door and run away?"
"No, of course not. Wouldn't be dignified for a future Time Lord."
She can tell by his smile that he knows she knows he's lying.