What is the plot of Burn Marks by Sara Paretsky? Who are the main characters?

Burn Marks is Paretsky's sixth novel with the main character V.I. (Victoria Iphigenia, or Vic) Warshawski, a Chicago-born private investigator. 
The characters include V.I., her on-again, off-again boyfriend, cop Michael Furey, her alcoholic Aunt Elena, and an old friend, Rosalyn Fuentes, who is running for a Cook County office.
Aunt Elena comes to Vic looking for a place to stay after arson has destroyed the downscale, single-room occupancy (SRO) hotel where she has been living.  Vic finds a room for her and her companion, Cerise.  Not long after Vic settles them in a new room, Cerise is found dead elsewhere, and Elena disappears.  Vic is hired by an insurance company to find the arsonist before it makes payment to the building's owner.
In the course of her investigation Vic is discouraged and threatened by most officials she encounters, including the head of the arson division, a building developer, and the owner of the burned SRO. She isn't sure who presents the biggest threat: someone in the police department, Cook County politicians, or construction developers. Her relationship with Rosalyn (Roz) Fuentes is strained because of issues of trust.
Ultimately, Vic finds her aunt and rescues her from another arson, but not until she has survived various pursuits and attempts on her life. She uncovers corruption in which politicians and developers collude.
Burn Marks hits many social criticism notes: paternalism in policing and politics, the greed of real estate developers, and anger at the living conditions of the poor in urban America.