What began as a desperate attempt to save lives became a descent into an abyss of deception, moral compromise and outright criminal acts.
Ah, yes, the reassuring sound of moral certainty being shredded. It is both well written and psychological. A particular recommendation for lovers of John Le Carre and shades of grey. More when I've read it all.
EDIT - there is a glowing review here
Speaking as someone with only a vague knowledge of DS9, the novel is accessible.