Henry Lamb works as a file clerk in a London office and secretly has a crush on his land lady. Shortly after his Grandfather has a stroke, Henry is "promoted" and goes to work for a secret government agency called The Directorate. It seems that for well over a century, the Directorate has been at war with the House of Windsor over a pact made with an tentacled alien god called Leviathan. From there, things get weird...
Wow. This was one weird read. It has a Tim Powers level of weirdness and also feels a bit like The Man Who Was Thursday
at times. There were lots of unexpected twists and turns. Henry Lamb is a good everyman character cast in the Arthur Dent mode. You feel for him as he gradually pieces together what's been going on his whole life. Barnes has grown as a writer since The Somnambulist.
I'd recommend this to anyone who enjoyed The Somnambulist, as well as fans of Tim Powers, G.K. Chesterton, and Grant Morrison's Doom Patrol.