"So where are we going this time?" Rose asks.
She looks down at the checklist she created before they had started.
"Mmmmm...the 2020 Olympic Games, check. Julius Caesar and Cleopatra? Met them just now, didn't we? Let's see...who haven't we visited yet...Mozart!" she exclaims.
Rose looks up, only to see that the Doctor does not share in her excitement. In fact, he looks rather nervous and uncomfortable.
"Are you sure?", the Doctor asks. "Isn't there any other time or place that you would rather want to go? We could swing by my old friend Winston Churchill, or Albert Einstein for that matter."
"But that would be ever so dull," she says. "I want to meet the most talented musician in history. Maybe he'll even write a song in my name - Vincent van Gogh was seemed happy enough to dedicate one of his paintings to me, remember that?" she adds teasingly and laughs.
"I suppose...if you insist," he says.
"Victory!" she shouts, tackling him into a very enthusiastic hug.
He forces a smile and says, "Well, don't get used to it."
As he sets the course of the TARDIS to Vienna, 1781, Rose watches him. It is as if he knows something she doesn't. He has always kept secrets, the Doctor, but this seemed like something entirely different.
"What's wrong?" she asks him.
"It's nothing," he says, attempting a smile. For a moment she sees something more in his eyes, a deep pain as if - but then it's gone, replaced by his usual carefree composure.
She doesn't completely believe him, but she trusts; so she lets it go.