The Specialists (The Classic Crime Library, #5)

"The colonel was right. You had to draw a line through mankind, a wavy line but a line, and on one side you had Good and on the other side you had Evil. There was good and bad in everyone, sure, and every shitheel was some mother's son, and it was all well and good to know this, but when push came to shove, it was just words; there was Good and Evil with no shades of gray and Judgment Day came seven time a week."

Meet the Specialists, five good men, Manso and Murdock and Simmons and Giordano...