In the final stretch of their journey for the Key to Time, the two Time Lords get mixed up in several feuds. First, that between methane miners and a local tribe ("The Power of Kroll"), then in a nuclear war involving neighboring planets Atrios and Zeos ("The Armageddon Factor"). And finally, as the Key is assembled, the Black Guardian rears his head! Also, the hosts discuss the passing of Nicholas Courtney, the fondly remembered Brigadier Alistair Gordon Lethbridge-Stewart.