Khmer Nationalist is a political history of Cambodia from World War II until 1975, examining the central role of Sõn Ngọc Thành. It is a story of nationalistic independence movements, political intrigue, coup attempts, war, and American intelligence. The rise of Cambodian nationalism, the brief period of Japanese dominance, the fight for independence from France, and the establishment of ties with the United States that kept Sihanouk on edge until his downfall—in all of these, as Matthew Jagel shows, Thành was fundamental.

Khmer Nationalist reveals how Cambodian nationalism grew during the twilight of French colonialism and faced new geopolitical challenges during the Cold War. Thành's story brings greater understanding to the end of French colonialism in Cambodia, nationalism in post-colonial societies, Cold War realities for countries caught between competing powers, and how the United States responded while the Vietnam War intensified.