Torchwood: Empire of Shadows (053)

In the far future of the Earth Empire, Torchwood is forgotten. So it's a surprise when Zachary Cross Flane of the Torchwood Archive finds himself summoned to the opening of the late Empress's Library.

Her son believes that the conspiracy which deposed his mother is still active and that the key to it is hidden somewhere in the library. But does Zachary want to find it?