A group of Australian SAS regiment soldiers are deployed to Vietnam around 1967/8 and encounter the realities of war, from the numbing boredom of camp life and long range patrols, raids and ambushes where nothing happens, to the the terror of enduring mortar barrages from an unseen enemy. Men die and are crippled in combat by firefights and booby traps, soldiers kill and capture the enemy, gather intelligence and retake ground only to cede it again whilst battling against the bureaucracy and obstinacy of the conventional military hierarchy. In the end they return to civilization, forever changed by their experiences but glad to return to the life they once knew.

Max Foster (Carl Betz), an American newspaper reporter, is in Hong Kong to assist a defecting Russian diplomat. In return for arranging an escape, the diplomat must turn over to Foster a diary revealing the true events taking place in China. While making his escape, the defector is killed ant the diary vanishes. The reporter sets off on a search for it, from Hong Kong to Australia. The chase ends in an action-filled climax, with the journalist finally meeting up with "That Lady from Peking" (Nancy Kwan) - the diplomat's daughter.