In Brussailes, since the spring, there has been a large number of egg thefts. Suspicions are directed at the parakeets: invasive, noisy, and disliked, they carry a bad reputation in their green plumage. The Parliament of Birds decides to clarify this matter and appoints three sparrows to investigate the involvement of these foreigners: Chantperdu, a daring and brash robin; Sept, a clever and moody crow; and Jaboterne, a lost pigeon recruited by an unfortunate series of events.