Romana and K-9 have stayed in E-Space to help an ancient and noble people, freed from their shackles. But first they must heal divisions in the ranks, and those who see a very different future for the Tharil race.
Lady Christina de Souza is crashing an exclusive party in search of a priceless diamond. Out in deep space, time travelers Jenny and Noah collide with a strange diamond-shaped vessel. What is Prism? And what does it want with the Earth?
In the footsteps of Sarah Jane Smith, Rani Chandra is investigating strange weather phenomena, calling on an old friend for help - Jo Jones. But UNIT is also on the case, led by science officer Jac.