Inside the City, the Idea Curate Bureau has calculated that every story is comprised of only 837 basic Ideas, essentially parsing the "DNA of stories." But after years of overuse and recombination, new variations are scarce. ICB Agents hunt down reformulations of these Ideas – called malgams – for the Bureau’s use and redistribution.

Some Agents use sex. Others prefer drugs or religion. Agent Callum Ziegler uses violence to convince writers to give up their words. And finding them in the first place means following the divining rod in his subconscious, attuned to the frequency of pulsating Ideas. But when Ziegler follows a smoking trail of bullets to a malgam, he finds what no one dared to believe in – a notebook containing Idea number 838 and the girl who wrote it.