For years, frontier lawman turned big-city senator Waxillium Ladrian has hunted a shadowy organization called the Set, who are kidnapping people with Allomancy in their bloodlines. Now he has a new lead: a stockpile of weapons bound for the Outer City of Bilming, supplied by the Set to stoke a conflict between the city and the corrupt Elendel Senate.
It's not the only weapon at the Set's disposal: Wax realises they have discovered a new and lethally powerful explosive, in addition to the backing of a god - Trell - to rival Harmony. Without any divine insight into events in Bilming, the only way to be sure if the Set are developing a bomb with the potential to level a city, or even destroy their world, is to visit the city in person..