Marked Man by John Florio

1971. Brooklyn, New York. Undercover cop Frank Serpico is knocking on a drug dealer's door. His partners are there to back him up, but when the door opens, he's staring down the barrel of a gun-and his partners are nowhere to be found.
For more than a century, the New York Police Department had been plagued by corruption, with cops openly taking bribes from gamblers and drug dealers. Not Serpico. He refused to take dirty money and fought to shed light on the dark underbelly of the NYPD. But instead of being hailed as a hero, he became a target for every crooked cop on the force.
In Marked Man, John Florio and Ouisie Shapiro bring this true story of police corruption to life. Join Frank Serpico on his one-man crusade to clean up the largest police force in the United States. And discover the price he had to pay for being an honest cop.