The TARDIS arrives in the CAGE – not a trap, but the College of Advanced Galactic Education, one of the most prestigious academic institutions in colonised space.

Not a trap. Or is it?

The Doctor's here to receive an honorary degree in Moral Philosophy. But there's something rotten at the heart of the Medical Facility. Someone is operating on the students. Someone without a conscience. Someone with access to a Sidelian Brain Scanner – a technology that hasn't been invented yet.

That someone is the ruthless Time Lord scientist known as the Rani – in her new incarnation. But will the Doctor and Peri recognise the Rani's hand before her trap is sprung?