EMILY BARNFATHER: It simply says to go to his study.

EMILY BARNFATHER: His study?

FOLEY: That's where he vanished, Miss.

EMILY BARNFATHER: I see.

DOCTOR: How can you be sure?

FOLEY: I can only tell you what I experienced, Sir.

FOLEY: I left the Professor there, it's a windowless room and he closed the door behind me. When I returned he was gone.

CHARLEY: A regular locked room mystery.