And run, they do, down the stairs, while alarms go off and the PA system announces a quarantine as doors slam shut on every floor. The Doctor's still shouting at her to keep going down, as though there were anywhere else to go. As if she were in any hurry to stick around.

They descend the last flight of stairs and burst through a door into the cellar, and Cassandra starts pushing the lift button frantically until the Doctor reminds her it won't work because of the quarantine.

"This way!"

She runs the other way, the Doctor on her heel, as well as a bunch of those plague people. She hears Chip whimpering somewhere behind her, but she can't stop, she needs this body safe, too. As long as she's in it, anyway.