HARRY: (To the DOCTOR.) Now we shall use the humans in the Cryogenic Chamber. SARAH: To Earth? The Wirrn were driven from Andromeda.
Plan: A: The Doctor; Q: Who tries to protect the humans? A: cryogenic suspension; Q: What are the humans in? A: their new breeding ground; Q: What do the Wirrn want to use Earth as? Summary: The Doctor tries to protect the humans still in cryogenic suspension from the Wirrn, who are determined to use Earth as their new breeding ground.