In the beginning of the book, Doctor Dolittle helps to capture a slave trader's ship, then organizes the postal service of a small African kingdom, Fantippo, ruled over by King Koko.

Mobilizing migrating birds to carry people's mail from continent to continent, Doctor Dolittle effectively anticipates the 20th century invention of air mail.

Over the course of later chapters, he discovers a hidden island populated by prehistoric creatures, gets thrown into another African jail, invents animal alphabets, and defeats at least two armies.

[2] The final segment of the book is the Doctor's journey to meet Mudface the Turtle, the oldest living creature on Earth, who survived the Great Flood.

The extensive tale of the Great Flood is presented in a later volume of the series, Doctor Dolittle and the Secret Lake, posthumously published in 1948.