Most good stories start with a fundamental list of ingredients: the initial situation, conflict, complication, climax, suspense, denouement, and conclusion. Great writers sometimes shake up the recipe and add some spice.
Exposition
Welcome, Stranger
We're introduced to the cast of characters, and learn about the encroaching tourists, Philoctete's leg wound, and the feud between Achille and Hector over Helen. We see Plunkett and his wife Maud in their house, learn of his war wounds, lack of children, and need to plunge into research about the island to give Helen (the island and the lady) a history. Walcott gives us a glimpse of his lost love and he meets the ghost of his father, who tells him to give voice to his people, whom history has ignored.
Rising Action
Dive into the Past
Major Plunkett's research confirms the connection between the Caribbean Helens (island and lady) and the ancient one. He also finds an ancestor whose history is wrapped up in St. Lucia's—Plunkett "adopts" the young man as the son he's never had. As one does.
Helen leaves Achille and moves in with Hector, prompting Hector to sell his canoe and buy a van to become a taxi driver. On Walcott's side: He's back in Massachusetts seeking character-inspiration. He finds Catherine Weldon and sees Achille in Winslow Homer's painting, and he also encounters his ghost dad again, who tells him he needs to travel.
Achille suffers sunstroke and takes a spirit-journey to the African settlement of his ancestors where, among other things, he learns his true name.
Climax
Paying History's Debt
Achille helplessly witnesses his people being taken into captivity. Walcott goes on his tour of European capitals, per Dad's request, and runs into Omeros in London. St. Lucia is changing, moving away from village life to cater to the tourists, much to Achille's annoyance. As for Hector, he dies in a car accident; Helen is pregnant with his child.
Philoctete's sore is unbearable, but won't be healed. Maud dies of cancer, and Walcott returns to St. Lucia and attends her funeral. He is led by Omeros/Seven Seas to the Underworld, where he has a frightening, yet cathartic, experience. Ma Kilman listens to the call of her ancestors through the ants and finds the plant that will cure Philoctete.
Yup, we have ourselves the point of no return for pretty much everyone here.
Falling Action
Baby Steps
Helen moves back in with Achille, who continues to battle the encroachment of tourism and commercial fishermen. Ma Kilman bathes Philoctete in the new concoction she's made and he is healed both physically and spiritually; he accompanies Achille on an unsuccessful journey to find new fishing grounds. Major Plunkett adjusts to life without Maud and gets a whole new perspective on the island and his place in it.
Resolution
A New Day
Walcott lets go of his lost love and gains a new perspective on his role as poet, as well as on his poetry. Achille and Philoctete perform ritual African dance on Boxing Day and Philoctete relives the pain of his ancestors through it. Achille wants to give Helen's baby an African name, but she won't do it—she does, however, get a job as a waitress at the Halcyon. Major Plunkett learns how to be with the people of the island and settles down more comfortably in the place he loves. Walcott and Omeros improvise poetry in praise of St. Lucia together. Because of course they do.