Gloria Marlowe, the US Consul in Singapore, hires adventurer and trapper Frank Buck to take her to Koala Highlands, a remote jungle area where a plane carrying a US secret agent in possession of stolen Japanese plans for invading Malaya and Singapore, has crash-landed when it got caught in a storm. The Japanese hire the kingpin of Singapore's underworld, G. B. Vonturgo, to stop them. He sends Buck's enemy, a big game hunter who takes pleasure in killing the animals he hunts, while Buck always brings his big game back alive.