In late October 1943, a battalion of U.S. Marines have landed on Choiseul Island to create a diversion for the impending Allied attack and invasion of Japanese-held Bougainville Island, north-east of the large island colony of New Guinea. Four are selected to carry out a reconnaissance patrol to find a French planter and his daughter who have valuable information on Japanese mine areas - information that can save the lives of 18% of the invading Marine force.