While the Royal Australian Navy evacuates Salamaua in February 1942 ahead of a Invasion of Lae-Salamaua, Commander#Royal Australian Navy Frank Houghton (Trevor Howard) coerces an old friend, American beachcombing Walter Eckland (Cary Grant), into becoming a Coastwatchers for the Allies. Houghton escorts Eckland to deserted Matalava Island to watch for Japanese airplanes. To ensure Eckland stays put, Houghton sees to it that his own ship "accidentally" knocks a hole in Eckland's launch (boat) while departing, so his only boat is its utility dinghy. To motivate Eckland, Houghton has his crew hide Eckland's whisky around the island, rewarding each aircraft sighting (once it is confirmed) with directions to one of the bottles.