Book 12 in the 25 book series of Tarzan stories.

NKIMA danced excitedly upon the naked, brown shoulder of his master. He chattered and scolded, now looking up inquiringly into Tarzan's face and then off into the jungle.
"Something is coming, Bwana," said Muviro, sub-chief of the Waziri. "Nkima has heard it."
"And Tarzan," said the ape-man.
"The big Bwana's ears are as keen as the ears of Bara the antelope," said Muviro.
"Had they not been, Tarzan would not be here today," replied the ape-man, with a smile. "He would not have grown to manhood had not Kala, his mother, taught him to use all of the senses that Mulungu gave him."
"What comes?" asked Muviro.
"A party of men," replied Tarzan.
"Perhaps they are not friendly," suggested the African. "Shall I warn the warriors?"
Tarzan glanced about the little camp where a score of his fighting men were busy preparing their evening meal and saw that, as was the custom of the Waziri, their weapons were in order and at hand.
"No," he said. "It will, I believe, be unnecessary, as these people who are approaching do not come stealthily as enemies would, nor are their numbers so great as to cause us any apprehension."
But Nkima, a born pessimist, expected only the worst, and as the approaching party came nearer his excitement increased. He leaped from Tarzan's shoulder to the ground, jumped up and down several times and then, springing back to Tarzan's side, seized his arm and attempted to drag him to his feet.
"Run, run!" he cried, in the language of the apes. "Strange Gomangani are coming. They will kill little Nkima."
"Do not be afraid, Nkima," said the ape-man. "Tarzan and Muviro will not let the strangers hurt you."

Genre: Thriller