Big Finish Productions is a British company that produces books and audio plays (released straight to compact disc and for download in mp3 format) based, primarily, on cult science fiction properties. They are best known for their Doctor Who line; other properties include the characters Judge Dredd and Strontium Dog from 2000 AD, Dark Shadows, Torchwood, Sapphire & Steel, Stargate, Blake's 7 and Sir Arthur Conan Doyle's Sherlock Holmes character.