Alan Moore - the genre-defining writer behind works including Watchmen, From Hell, Jerusalem, and the short story collection Illuminations - has officially announced his next project, The Great When, revealing the book's mind-bending cover. Moore has long teased his plans for the 'Long London' quintet - a series which will follow an 18-year-old protagonist whose story will stretch across several different time periods in the UK's capital city, beginning in 1949.

Publisher Bloomsbury has now confirmed The Great When will release October 1, revealing the book's cover and blurb. The novel will follow second-hand bookseller Dennis Knuckleyard as he discovers that one of the rare books he's been asked to acquire doesn't exist, plunging him into the hidden magical underworld of London, known as the Great When. Now, fans get to see the full wraparound cover, exclusively shared by Entertainment Weekly, with Moore calling it "a small illustrative masterpiece that perfectly reflects the book's hallucinatory mood and storyline, along with that of the post-war decade the work is set in."