Mike Yates invites Sarah to visit him at a Buddhist center where he’s been staying since his resignation from UNIT. He suspects evil is afoot there…
The TARDIS returns the Doctor to Peladon at a point in time fifty years after his last visit and is arrested by Chancellor Ortron for trespassing in the sacred temple of Aggedor.
Landing on planet Exxilon, the TARDIS is drained of power and an expedition from Earth is also stranded. But when a third ship lands, its occupants are revealed to be Daleks.
Landing in London the Doctor and Sarah are puzzled to find the city deserted. Arrested as looters, they are eventually found by the Brigadier and brought to UNIT HQ.
Journalist Sarah Jane Smith poses as her aunt, virologist Lavinia Smith, in order to gain access to a research center where top scientists are being held in protective custody.