Main Force Assault follows the Marines and Popular Forces of Combined Action Platoon T-9 as they continue their mission to protect the villagers of Bun Hou from the Viet Cong, and from corrupt South Vietnamese officials. Following the combat in the first book in the series, Knives in the Night, CAP Tango Niner has several replacements, including a new lieutenant, who has to be taught how to be a leader. The action here is sometimes hotter and heavier than in the previous book, but not everything is combat. The Marines find themselves having to deal with a sometimes mindless bureaucracy, and the attendant difficulties in getting things they need. There is a "midnight requisition" of a jeep, and a love interest is introduced as well. The way the Marines in the unit deal with the day to day realities of life in a CAP is true to life. It's always good to remember that Marines aren't supermen, they're simply men doing a very difficult, very dangerous job, and doing it very well, as is shown in the gritty combat scenes.