The Worlds of Big Finish was a 2015 audio anthology from Big Finish Productions. It was a crossover of several of their ranges, some related to Doctor Who and some not.
From the streets of Edwardian London to the corridors of a near-infinite library in the distant future, a single book holds the key to the fate of life on Earth.
Some believe it predicts our future – and the apocalypse - with unnerving accuracy. Others will stop at nothing to destroy it, and will chase it from one side of the universe to the other; from a country house in the Roaring Twenties to the casinos of Mars, and from 221B Baker Street to the terrifying desert world of Sisyphus IX...