The Inquisition GM's Guide is a 144-page hardcover supplement, and the second of two faction-focused supplements for the Imperium Maledictum line. Within GMs will find expanded lore sections including deep dives about the various philosophical movements within the Inquisition, alongside advice on how to build spycraft-focused missions and campaigns. They'll find a roster of interesting characters, from Threats to character Contacts, and profiles on the six most prominent Inquisitors in the Macharian Sector, that can act as your player's Patron, allies or enemies. Tying the book together is the Heresies Macharia, a massive decades-spanning seven-part campaign wrought with heresy, mystery, and betrayal.