Disgusted by the endless lawsuits, political wrangling, and corruption of Athens, two aging citizens named Euelpides and Pisthetaerus decide to leave their home behind. Guided only by a crow and a jay, they seek out Tereus, the Hoopoe, who was once a human king and now rules the kingdom of the birds. Upon meeting the birds, Pisthetaerus proposes a brilliant and audacious scheme: the birds should build a great fortified city in the sky between earth and heaven. By surrounding this new aerial metropolis, called Cloud-cuckoo-town, the birds can intercept the smoke of all sacrifices rising from mankind to the gods. Starved of the smoke and prayers that sustain them, the Olympian deities will soon be forced to surrender their supremacy.
The birds enthusiastically embrace the plan, and under avian labor, the massive cloud wall is swiftly erected, cutting off all communication between gods and men. As news of the successful utopian experiment spreads back to earth, a parade of opportunistic charlatans, poets, prophets, and informers arrives, hoping to exploit the new society, but they are quickly driven away by Pisthetaerus. The blockade works precisely as intended, reducing the gods in heaven to severe distress and near starvation. Soon, a desperate delegation of divine ambassadors arrives from Olympus, consisting of Poseidon, the gluttonous Heracles, and a crude tribal god, sent to sue for peace.
Pisthetaerus drives a hard bargain during the negotiations, refusing any terms that do not restore absolute power to the birds. When Poseidon balks, Pisthetaerus slyly manipulates Heracles by convincing him that as a bastard child, he stands to inherit nothing from Zeus under sacred law, whereas the legitimate gods will take everything. Persuaded by this legal argument and the promise of a magnificent feast, Heracles switches sides and votes with Pisthetaerus, forcing the delegation to capitulate entirely. The gods surrender the ancient sceptre of the universe to the birds, and Pisthetaerus secures the hand of Basileia, the personification of royal dominion, in marriage.
The comedy concludes with a triumphant wedding celebration filled with choral songs and joyous hymns. Pisthetaerus ascends to rule the cosmos from the heavens alongside his divine bride, wielding the very lightning bolts once reserved for Zeus. The birds achieve ultimate sovereignty over both mortals and immortals, establishing a new order where human worship is redirected entirely to the feathered kingdom. Through its imaginative scale and theatrical splendor, the play delivers a lasting vision of rebellion against earthly tyranny and celestial hierarchy alike.