The narrator-protagonist Cyrano, nicknamed for his large nose, recounts in the first person the events of the most important day of his life, a day he spends preparing a lecture he must deliver that same evening. Although his announced topic is the mythic structure of the hero, that morning he rejects it for an altogether different topic, one he hopes will hold the interest of his wife Carmina's sister Rosita, with whom he has been having an affair for some years. Hoping if not to seduce Rosita, at least to make their last encounter memorable, Cyrano decides to speak in his double vocation as writer and spy and the similarities between the two professions.