 As the TARDIS heads to the paradise planet Florana where the Doctor and Sarah go for a holiday, the TARDIS goes off-course and arrives on the barren planet Exxilon, where the TARDIS is loosing power. The Doctor and Sarah finds a group of humans and Daleks are searching for Parrinium, a mineral which is the only antidote to a space plague. Where the Doctor enters the Exxilons lost city, in hoping he will find the Parrinium, as both the Daleks and the humans are loosing power.