DOCTOR: Which way, do you think?

ZOE: To the right.

DOCTOR: They both look equally unattractive to me.

ZOE: But it must be to the right. I've been working it out as we went along.

JAMIE: Doctor.

DOCTOR: Shush. How?

ZOE: Well, as soon as we avoided the dead ends, it soon fell into a clear pattern. One left, two right, three left, four right and so on. It's a simple arithmetic progression.

JAMIE: Yes, but Doctor.

DOCTOR: Shush, Jamie.

DOCTOR: What it is to have an arithmetical brain. What do you want?

JAMIE: The thread's run out. Now, should we not go back?

DOCTOR: No, you stay here.

JAMIE: Ah.

DOCTOR: And Zoe and I will explore a little further. There must be another way out of this maze and I mean to find it.