Following the Japanese invasion of the islands in 1942, North Luzon was the staging area for several Filipino-American guerrilla bands who sought to gather intelligence and to destroy enemy military installations or supplies. Bernard Norling focuses on the Cagayan-Apayao Forces, or CAF, commanded by Maj. Ralph Praeger. Their bravery was unquestionable, but by September 1943 all but one member of Troop C had been claimed by combat, enemy capture, or disease. The only survivor, Capt. Thomas S. Jones, remembered, "Defeat is a terrible thing.... It brings down with it the whole structure about which a nation or an army has been built. It subjects men to the most severe of moral tests at a time when they are physically least able to meet them."

Based primarily upon unpublished sources, The Intrepid Guerrillas of North Luzon includes the diary of Praeger's executive officer, Jones, and draws on transcripts of radio communications between Praeger and General MacArthur's headquarters in Australia. The struggles of the men of the CAF tell a harrowing tale of valor, determination, and occasional successes mixed with the wildcat schemes, rivalries, mistrust, and betrayals that characterized the intramural relations of guerrilla forces all over the Pacific islands.