Sergei Lukyanenko. Night Watch (№ 211608)

That's just the most honest and ingenuous COP, raised on loud star-spangled ideals, sooner or later will realize: the streets have not only Darkness and Light. There are more understandings, concessions, agreements. Informants, traps, provocations. Sooner or later you have to take her, to throw into other people's pockets bags of heroin, beat on kidneys, gently, leaving no residue.
And all for the sake of those simple rules.
To uphold the law. To Pursue Evil. To protect the innocent.