US Consul in Singapore hires adventurer Frank Buck to take her to 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.
The Japanese kidnap Buck's friend, the Sultan of Johore, who saw their fake archaeological excavation site. Gloria and Buck must figure out what the codename for the Japanese invasion - Seven Keys to Singapore - means and sabotage it.
Count Markoff offers 5 thousand dollars for an ebony cat (black panther) delivered by Friday. Frank Buck competes against his old mentor Dingo Larson, with whom he had a falling out. Meanwhile, Gloria is coping with a jewel thief at the Raffles Hotel.
Filmmaker Flynn wants to make movies starring Frank Buck, who reluctantly agrees to have Flynn accompany him on a trip to the Valley of the Mists. The peaceful tribe that lives there is coping with some unwelcome European visitors.
Buck helps a young missionary and her charges escape from Japanese soldiers while trying to reach Gloria to warn her about a spy who has infiltrated an important conference at Raffles.
Frank and Gloria's plane goes down in cannibal territory. While they try to get home, they remain unaware that Buck has been infected with cerebral malaria and needs to get treated as soon as possible.
Down on his luck WIlmer Bass sells his trained lion to Frank Buck. Neither of them realize that the animal's collar is the fabled collar of Katumba that a dangerous cult is searching for.
After escaping from jail, Bundhi is forced to deliver a priceless necklace for Vonturgo and ends up chained to Frank Buck along the way. Meanwhile Gloria is equally desperate to get the necklace back.
Princess Kati, an old friend of both Buck and H.H., is about to become Sultana. However, some of her staff are plotting against her and various attempts are made on all three of their lives.
Frank Buck finds an old journal that may lead to finding the bones "Singapore Man", possibly the missing link. Anthropologist Laura Davies arrives as soon as she can, but there are several other parties after the bones as well.
Gloria counts on Frank Buck to guide an important visitor from Washington going by the name of Marsh. Two sets of German spies are after March, one of which has switched his suitcase for one carrying a bomb.
While on a romantic dinner date, Frank Buck and Stacey Martin are drugged and she is kidnapped to be sold off to a Raja. Frank and H.H. go in pursuit to get her back.
H.H. is captured by the Chinese Triad and held for ransom for one of their own. Buck reluctantly teams up with reporter Dana Miller to safe the life of his friend.
Frank and a female photographer from National Geographic are captured by Banjee tribesmen. To their surprise, an ex-convict called Harry Larkin leads the tribe.
Frank Buck is expecting H.H. to throw him a birthday party. But beforehand, he is subjected to several attempts on his life. Things get even more complicated when a storm hits Singapore and Buck's birthday present escapes.
