Incendiary Designs — Michael Allen Dymmoch

With “terse prose,” this “fascinating” entry in the award-winning series pits psychiatrist Jack Caleb and cop John Thinnes against a serial arsonist (Library Journal).
 
While jogging through Chicago's Lincoln Park at dawn, Dr. Jack Caleb comes upon a scene of horror -- a mob in white robes about to set a police car on fire with the officer inside. Caleb's training as a medic in the Vietnam War kicks in and he rushes to rescue the man. One cop is saved, but later his female partner is found in another location, stoned to death. Homicide detective John Thinnes has a cop killer on his hands.
 
But these two attacks are only the beginning in a series of arson fires and murders over the course of a long, hot, deadly summer. Evidence points toward cultists in the Church of Divine Conflagration -- but then some of them also fall victim to the pyromaniac. When a physician friend of Caleb is implicated, the psychiatrist works with Thinnes to set a trap for the killer -- but it's one they might not escape unscorched themselves . . .