For the city (and the author) it was a year of trauma, possibly the most traumatic in NYPD history. The so-called Black Liberation Army shot cops in the back. In New York alone they assassinated four, machine gunned two others, ambushed others with guns and knives. A new commissioner, swearing to end corruption and bring the force into the modern age, took over, even as two mafia dons got whacked, the biggest jewel robbery in the city's history took place, and Sgt. Durk and Patrolman Serpico brought on the Knapp Commission, whose purpose was to put cops in jail. Meanwhile, in the corridors of headquarters men with stars on their shoulders undermined the new commissioner where they could while jostling constantly for position and power.