The Exploding Planet

The TARDIS materialises on a doomed planet in Galaxy 4, and the travellers are captured by warriors of the beautiful female clone race known as Drahvins. According to the Drahvins' leader, Maaga, their ship was shot down in an unprovoked attack by the vicious alien Rills, but they managed to inflict damage on the Rill ship as well; now both ships are stuck here, on a planet doomed to explode in fourteen days. Maaga orders the Doctor to help her and her warriors capture the Rill ship, and keeps Steven hostage to ensure his co-operation; however, the Doctor soon learns that Maaga is both lying and mistaken. The Drahvins are in fact the aggressors, and the peaceful Rills want nothing more than to escape in one piece - and help their enemies do so as well, if they can. Unfortunately, that may not be possible, as the Doctor discovers that time is shorter than they thought; the planet in fact has less than a day of life remaining...