The Brotherhood — Patrick J. O'Brian

After the untimely death of his father, Mike Sheridan learns to live again. A city firefighter working near Chicago, Sheridan enters a particularly perilous summer where everything is not as it seems. His nephew is baptized into the fire department, unaware of the political dangers, coupled with a clever arsonist, who can make any fire or explosion look accidental. Sheridan finds himself combating a new volunteer fire department created through a political rift, which holds nearly as many dangers as the arsonist drawing Sheridan and his two firefighting brothers into danger over the course of the summer. Keeping a promise to his father to bring his family closer together becomes all the more difficult when the arsonist's work harms someone close to him. Realizing the law can't, or won't help him, Sheridan seeks out the man responsible at any cost.