"The Beasts of Tarzan" (Tarzan #3) by Edgar Rice Burroughs

As THE BEASTS OF TARZAN begins, Tarzan -- as Lord Greystoke -- is settled in civilized London. But two of his enemies, Nikolas Rokoff and henchman Alexis Paulvitch, are on his trail. The pair abduct Jane -- and Tarzan's son, Jack. Tarzan himself is stranded on a desert island, but with the help of Sheeta the panther and Akut the great ape, he makes it back to the mainland. There he meets Mugambi, the giant chief of the Wagambi tribe, who becomes Tarzan's lifelong friend and ally. The group heads into the deep jungle after the kidnappers -- and when Tarzan finds them, he lets the beast inside him wreak his vengeance. There's a beautiful irony here -- Tarzan has come from the jungle into civilization, and his son must go from civilization to the jungle. Where Tarzan grew up without human guidance or moral direction, he has become an honorable man -- chivalrous, almost noble; a genuinely good man. And now his son, raised in civilization, must now walk a similar path. . . .