The Mockery Bird takes place on a tropical island called Zenkali. The island seems to be populated by the most eccentric people who came there from all around the world, along with the two indigenous tribes, the Fangoua and the Ginka. The Ginkas used to worship a dolphin god, while the Fangouas worshipped a strange avian, the Mockery Bird, which was hunted to extinction by the former French colonizers. Zenkali is ruled by King Tamalawala III, usually referred to as "Kingy" by his people. Peter Foxglove arrives to Zenkali to be the assistant of Hannibal Oliphant, Kingy's Political Advisor. Zenkali, once a British colony, is about to get self-government. They are also planning to construct a military base, an airport and a power station, and this will mean the flooding of a large, unexplored valley, owned by the villainous businessman, Looja. Peter, along with the beautiful Audrey Damien, visits the valley before it is totally destroyed, and makes a fantastic discovery: a small population of Mockery Birds still live in the valley. Peter's discovery attracts the attention of the world press, environmentalists, politicians and businessmen from all around the world, and this leads to a couple of adventures. Finally, Professor Droom, a biologist, discovers that the main and only agricultural product of Zenkali, the Amela tree is ecologically linked to the Mockery Birds (explained below), so the flooding of the valley will make the island's economy collapse. Consequently, the construction of the airport is cancelled.

The Mockingbird is a story about the very first birds that God created back when time began. When called to the tree in the garden to receive their songs, one feathered character arrived late and missed out completely. The story explains what happened next and why he is called the Mockingbird.