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The episode also features Oswin Oswald, a young woman trapped on the Asylum following a spaceship crash.

It transpires that she has in fact been converted into a Dalek by the nanogenes to preserve her genius-level intellect for Dalek use, having created the self-delusion of continuing humanity to protect herself from the horror of her condition.

Ultimately Oswin is able to overcome her re-emergent Dalek personality and assist the Doctor and his companions to escape the planet, at the same time removing all knowledge of the Doctor from the Daleks ’ collective memory.

She apparently perishes when the Daleks destroy the Asylum from space.