Lovely place. Streets were lined with rubies, literally. It seemed like the right sort of place to take Rose Tyler for a trip. Land somewhere within the principal city of Vertias, have some lunch and wander around a bit.
Really, though, now that the Doctor thinks about it, he should've taken at least a brief glance at the books he had on Zelmenoxian law before landing there. Not twenty minutes after they started wandering, they were approached by one of the half-horse aliens (a police officer, in fact) and asked if they'd taken the Vertian Supplement, required of all citizens and visitors.
The correct answer was "no" and the Doctor was regretting saying that. Now, they sat in a Vertian cafe, looking over some of the custom guides to figure out exactly what they'd been injected with.
"It's a truth-telling serum," the Doctor announced, looking over the edge of his glasses at his companion. "To try to sort out the 'primary question of the universe'. Whatever that could be."