Based on a 1994 Doctor Who novel, All-Consuming Fire sees Sherlock Holmes, played by voice-of-the-Daleks Nicholas Briggs, called in by the Vatican when some of the most dangerous books in the world are stolen from the Library of St John the Beheaded.
Sylvester McCoy returns as the Seventh Doctor alongside companion Ace (Sophie Aldred), while Sherlock Holmes aficionados will also appreciate the inclusion of a character named Sherringford Holmes – the original name of Sir Arthur Conan Doyle’s literary creation.
They kinda neglect to mention that Big Finish has had a Sherlock Holmes audio series going for several years, adapting both original Doyle stories and tacking on a few originals, with Briggs as Holmes. So it’s not quite as out-of-nowhere as they might make it sound.
And yes, the Old God they’re mentioning is indeed a Lovecraftian one.