A major American fun­da­men­tal­ist preacher has drawn dis­turbing­ly close to the British Prime Minister, and the more the Laundry looks, they more alarmed they become. Hacker/com­pu­ta­tion­al de­mo­nolo­gist/Laundry agent Bob Howard is leveling up with the Laundry and he has been assigned to “External Assets”, the wing that deals with deniable freelance agents. Bob, Persephone Hazard, and Johnny McTavish are sent to Colorado to in­ves­ti­gate Golden Promise Ministries. There they find a hidden cult within the church where the members are possessed by alien parasites that are trying to hasten the Apocalypse by summoning a chained monster from another dimension.

Sequel to The Fuller Memorandum. More at Charlie Stross’s Crib Sheet and the Laundry Files Wiki.