While watching The Mindscape of Alan Moore, I could almost pass him off as an English eccentric. He certainly has that neo-post-punk hippie thing going on and it doesn't help he's introduced as writer and shaman. He actually refers to himself as a magician but he soon makes it clear his magic is the manipulation of perceived reality through the use of words. Once he explains his philosophy his eccentricity is charmingly gothic and you know you'd be happy to share an ale or a pot of herbal tea. I like to think of Moore as a nice version of Alistair Crowley.
Moore's mindset is very English left; his political views were born from the time of Thatcher's Britain. He has a passionate distrust for government and believes they'll do whatever they can get away with. Read any of his works, especially Watchmen, From Hell or V for Vendetta and that soon becomes evident. You'll also notice he often draws upon English history to build his past, present and future distopian fantasies and the world of Victorian England is where The League of Extraordinary Gentlemen resides. It is a team of Victorian fictional characters, Alan Quartermain, Mina Harker, Captain Nemo and others, who under the direction of the British Government act as a Justice League for the British Empire.
In the first two books the league confront Fu Manchu, Professor Moriaty and even H G Wells' own Martian horde. But it's no thrill ride adventure as the characters find reasons to distrust their masters, the institutions, each other, even their own principles. Moore pushes this even further in the latest, The Black Dossier. But that's not all he pushes. Unlike the previous first and second volumes, Black Dossier is not a compilation of a comic book mini-series, it is a single self contained work that very much plays against the norms of graphic novels.
Black Dossier jumps from the Victorian times of the past volumes to 1958, a year after the fall of Orwell's Big Brother. The graphic novel part of it deals with two people discovering the dossier and being pursued by conspiratorial entities. The other part of the book is an excerpt of the Black Dossier itself. That includes stories in different styles, comics from different eras, a Shakespeare play, a Tijuana Bible, maps, diagrams and a 3-D section (with glasses). How this all ties in with the League of past volumes you'll have to find out for yourself.
It is an ambitious and most diversified work that has Moore yet again challenge the pre-conceived notions of the graphic novel. And other than its surface appearance as a companion to the first two books, it might be better described as an intertextual conglomeration of coded pastiches. However, I think I'd just call it a pretty darn clever bit of writing and drawing. The film The Mindscape of Alan Moore may well take you into Alan Moore's unique thought processes, but how he applies that to works like The Black Dossier is where his mantel of genius truly resides.