In Louie's Sweet Shop, Sach assists a police officer in recovering a bag of stolen diamonds by sniffing them out, then realizes that his sense of smell has been heightened by new antibiotic pills he is taking for a sinus condition. The owner of the diamonds, Alf Grimshaw, tells Sach and his pal Slip that they can become rich by using Sach’s olfactory talent to recover a horde of lost diamonds in Africa. Grimshaw, Sach, Slip, and their friends Louie, Chuck and Butch then journey to Africa or, as Slip calls it, “The Dark Condiment.” They meet Grimshaw’s partner, the ailing Holmes, at his trading post where he explains how another of their partners had found the diamonds, but was killed before he could tell Holmes where they were hidden. Before Holmes became ill, he and Grimshaw had searched the area, but had only been able to establish that the diamonds were hidden in a complex of caves. Dr. Goebel, Holmes’ physician, is present when Holmes gives Sach a map of the route to the caves and warns him to guard it with his life. Later, Goebel and his crooked confederate, Shanks, decide to follow the expedition to the caves and steal the diamonds. The group sets off and on their first night in the jungle decides to build several fires to ward off lions. After Sach inadvertently uses the map to start his fire, he conceals the fact that it is been destroyed and instead leads them aimlessly in circles. Goebel, Shanks and their bearers are also following the same bewildering trail. After days of wandering, Sach admits that the map is gone and that the paper he has been consulting is actually a mail-order girdle advertisement. The contrite Sach threatens to commit suicide, but changes his mind and is relegated to the rear of the group. As they stumble on through the jungle, a lion threatens Sach who is then rescued by Anatta, a curvaceous jungle woman who becomes enamored of him. When the others return to find Sach, Anatta runs away, and after the bearers see the dead lion, they assume that Sach killed it and proclaim him a great white hunter. Meanwhile, Goebel and Shanks visit Omotawa, a native chief, and arrange that he will kill all the strangers, except the one with the big nose. After the chief takes the boys prisoner, Goebel informs them that he and Sach will go diamond hunting the next morning while Slip and the others are turned into shrunken heads. Slip realizes that the only way they can escape their predicament is by disabling Sach’s sense of smell, so they ensure that he catches a cold. The next morning, as Sach sneezes, Slip informs Goebel and Shanks that Sach cannot smell anything. Goebel and Shanks then take Sach to their hut where Rangori, the masked witch doctor, tries to cure his cold. Soon after, Anatta appears and knocks Rangori out, after which Sach dons Rangori’s mask and robes and frees the others. After Sach recovers from his cold, Grimshaw convinces Anatta to take them to the caves, which are reputed to be haunted by a faceless ghost. Inside one of the caves, Sach and Slip collide, disabling Sach’s nose when they hit their heads together. Sach accidentally finds the horde of diamonds, however, when he is chased by the ghost. Goebel and Shanks arrive and hold the group at gunpoint until the ghost reappears, enabling the boys to overpower them. The ghost is revealed to be Holmes, who has been tracking Goebel and Shanks, after having discovered that they had killed his partner. Later, as Slip, Louie, Chuck and Butch prepare to leave on a boat, they wave goodbye to Grimshaw, Holmes and Sach, who has donned a loincloth and decided to stay with Anatta. When Anatta’s boyfriend, who looks like Tarzan, shows up, Sach runs off to join the others on their trip back to the Bowery.