After the Doctor spoke, Cayce bowed her head and rubbed her hands over her face. For a moment she looked almost as if she might be about to cry.

Then, when Psyche answered, she looked up; her eyes were dry, and the determined set of her jaw had returned.

"Standard timekeepers won't work," she said. "Barring some other solution," a quick glance at the Doctor, "what would be really great is a pair of people who can communicate telepathically. One on the surface and one underground. Don't suppose we've got any of that here?"