It's set in a mythical Welsh town -- Thomas's original name for it was Llarregub (a name that looks like that of a Welsh down, but it actually "bugger all" backwards). People have argued about which actual town it was meant to represent, but that's beside the point -- it is at once any town and no town, a place that exists only so far as its voices describe it, and just as they describe it.
We begin at night, with the dreams of the residents, wake up and wander through their mornings, and eventually reach the point just before the next night -- twenty-four hours of internal and external thoughts, monologues, and dialogues. Besides the narrator, a few figures seem most prominent, particularly "Captain Cat," who opens the night sequence with a dialogue with his sailors who have drowned, his "dead dears," rings the morning "wake up bell," and climbs back into his bunk near the end. But there are others -- very many others -- who endear themselves to our ears -- Organ Morgan whose thoughts return ever to his organ and the works of Bach; Mrs. Ogmore Pritchard who sleeps with one dead husband's ghost on either side, nagging them both; Lily Smalls, a housemaid in a "small" house with outsized dreams; Sinbad Sailors the barman, who has named his pillow after the girl he can't marry; and Mr. Mog Edwards whose love for Myfawny Price is known only through his letters, which are surreptitiously steamed open by Willy Nilly the postman and his wife.
Throughout, Thomas's poetic language juggles the senses, turning nouns into verbs and adjectives, playing with sound and sense, and heaving the whole dollop of humanity that is Milk Wood into his catch-net of wild words. So have at a few -- pick a character, a phrase, a moment -- and give us your thoughts below:

