The TARDIS is catapulted into a parallel universe where Rose discovers that her father, Pete, is still alive. A successful but childless man in this reality, Peter Tyler is in business with the wealthy and powerful John Lumic, the owner of Cybus Industries, who is seeking to stave off his terminal illness by any means necessary. At the same time, Mickey learns that his counterpart, Ricky, is the leader of the Preachers, a resistance movement trying to prevent Lumic from giving humanity the ultimate upgrade. Much to the Doctor's horror, Lumic's plan is one which he has seen executed before: the creation of the Cybermen!