The film tells of the beginnings of the Serengeti National Park in Tanzania. At the end of the 1950s, the Tanzanian national park administration wanted to fence off the protected area around the Ngorongoro Crater. Bernhard and Michael Grzimek were invited by the national park administration in 1957 to get an accurate picture of the animal migrations and to provide the national park administration with the values it needed for its project. Using a new counting method with two airplanes, the Grzimeks found that the herds' migrations were different from what had been assumed.