Mystery-writer Pronzini has worked up a lively, though frankly propagandistic, novel from Anderson's notes about genocide in Southeast Asia--with Cambodians dying by the hundreds of thousands in 1975's civil war when the Communists took power. The setting is Phnom Penh, a city that's been under siege for six weeks, where Than Kim, death-weary Khmer mistress of American diplomat (and CIA agent) David Foxworth, tries to ignore the horrors: ""If we cannot have peace and happiness, then we must pretend we have them."" While these lovers walk in sunlight, bloated Khmer bodies float downriver beside them. But Kim's adoration wanes as she sees that David is a robot without a single idea of his own, and when Phnom Penh falls, she refuses to accompany him to safety in Bangkok, preferring to believe that the Khmer people can absorb the Communists and recover peace. Also on hand in Phnom Penh are a wealthy young inspector for the Refugee Relief Fund, Natalie Rosen, and drunken leftist reporter Peter Deighan, who has been washed out by three years of massive death. And these two are among those who head for Thailand when Field Commander Chey Han (Kim's long-lost half-brother) leads the Communist troops into Phnom Penh: three million Cambodians are ejected from their cities, most of them to be slaughtered in death marches and ghastly relocation trains. The Khmer Rouge captures fleeing Kim and pumps her for names of educated Khmers (all will be killed); she is raped and befriends an orphan girl, who dies; and finally she has a recognition scene with Chey Han. Meanwhile, in Bangkok, David falls for Natalie, quits the diplomatic corps, and takes up refugee work; Peter, too, comes of age--by sobering up and writing The Rape of Cambodia (thanks to wife Carol, who is terminally ill with blood cancer). These are all, in fact, stock characters going through stock transformations; and Anderson's files don't really add significantly to what has previously been reported on those 1975 horrors. Still, it's a serviceable patchwork altogether--with some built-in extra grab in the Anderson byline.