Foundryside by Robert Jackson Bennett

Sancia Grado is a thief.  She lives in Foundryside, a slum which is home to all those considered not worthy of living in the gated merchant enclaves that make up most of the city Tevanne.  Sancia wasn't always a thief, although she has a hard time remembering her life before being one.  She knows that she was a slave on one of the plantations and she remembers pain and fire. 

Sancia has talents that the average person does not.  She can touch things like walls and receive data, knowing where the weak spots and footballs are.  This ability is the reason she is known in Tevanne as the master thief to hire if the job is difficult.  Sancia is hired to steal a small box for an enormous sum.  She accomplishes the task and that is where her life change begins.

What she has stolen is an artifact of the old masters.  It is a key and it begins to talk to her, introducing itself as Clef and telling her about its ability.  Clef can open any door.  Most doors are sealed by magic as magic is the ingredient on which all the great merchant houses are built.  The houses employ scrivers who have the ability to program inanimate objects and change their properties.  Clef can talk to the object and find the weakness in its program that allows him to change its function. 

Sancia soon realizes that she has an object that is in high demand, one that others will kill to obtain.  Clef is the necessary piece that will allow the unlocking of all the knowledge of the old masters, and the ability to force every individual to the powerholder's will.  She must form an alliance with unlikely allies such as Gregor, a soldier born to the elite class who wants to bring justice to Trevanne, and Orso and Berenice, scrivers employed by the house Gregor comes from.  Can this group thwart the plans of those who want to enslave humanity?

Robert Jackson Bennett is considered one of the best young fantasy writers.  He has twice won the Shirley Jackson Award for Best Novel.  He has won an Edgar for Best Paperback Original and a Philip K. Dick Citation Of Excellence.  This novel is the beginning of a new trilogy.  The plot is intriguing but the main interest comes from the characters who populate his world.  This book is recommended for fantasy readers.