Detective Brian McKenna is back from his bureaucratic desk job to his old Manhattan beat. He barely has a chance to readjust to the fast-paced life of a detective before he is assigned to investigate the death of a homeless man – who seems to have frozen in his sleep. Although it’s one of New York’s coldest winters, the mounting cases of homeless deaths are a mystery. Working with Maureen Kaplowitz, an older detective with an intuitive sense, McKenna discovers an odd coincidence: Many of the deaths classified “by natural causes” have been homeless men infected with the HIV virus. McKenna suspects a murderer is at work, targeting the most forgotten members of society. To stop the killings, he must uncover the killer’s identity – hinted at in a letter he signs “Hyde” – his deeply personal motive, his meticulous method, and the shocking secrets of his past.