Books in the Doctor Who: The Lost Stories series in order

The Doctor, Romana and K9 find themselves at the centre of a most unusual trial when an intergalactic corporation wants to bulldoze planet Earth for a development project. If The Doctor can Earth contains intelligent life, the whole world will be saved. But with a fortune at stake, it was never going to be that simple.

During one of Nyssa's experiments, the TARDIS's temporal scanner picks up a message: 'Idra'. Just one word, but enough to draw the Doctor to the Archipelago of Sirius. There, the Autarch is about to announce a new crusade. A mighty war against Seth, Prince of the Dark...