The play is set in 1961 on a remote island in the middle of the Atlantic, as far from South Africa in one direction as from South America in the other. The tiny community’s only contact with the outside world is a ship that visits approximately every six months.

Francis returns to the island having left for South Africa. Mill has never left the island and is desperate for yet nervous of her nephew’s return. Her husband Bill is more concerned about the meaning of a fearsome noise he has heard under water while swimming in the lake. With Francis is Mr Hansen, a businessman, who has come to propose to the islanders that he build a factory on the island to process crawfish. As leader of the island community Bill will be influential in the decision to accept the factory.

Francis meets his ex-girlfriend Rebecca who he left behind on the island. She is pregnant. He tells her how he hated the outside world and that he loves her.

Bill is making his will because he is worried about the noise in the lake. He tells Francis that he will encourage the islanders to accept the factory if Francis will listen to the noise in the lake.

Mill is excited by the idea of the factory and is disappointed when Francis dissuades the islanders because he has decided he cannot live there. Mill tells Bill she will leave if Francis does.

Bill persuades Rebecca to tell Francis that he (Francis) is the father of her child, but in return she makes Bill promise to kill the baby at birth. Francis remains on the island to marry Rebecca. On their wedding day Rebecca gives birth and the island’s volcano erupts violently. Bill kills the child. When Mr Hansen and Mill come to persuade him and Rebecca to board the ship to be evacuated, Bill tells them what he has done. Mill takes control and tells Mr Hansen never to reveal their secret.

Evacuated to Southampton and working in Mr Hansen’s factory, the islanders are homesick. Bill is finding his work in the boiler room different to the island and difficult. Mr Hansen tells Mill that the islanders can’t return home because the volcano has destroyed their island. Mill decides that they need to send someone to see the island, but realises that Bill is unable to help her. Rebecca finds that Francis is growing more distant.

Mr Hansen tries to persuade Mill not to make the trip home, although she has saved the necessary money. Francis tells her the British won’t let her go. Rebecca tells Mill that a journalist knows of a terrible secret about the island and Mill decides to use it to get the passage to the island.

Mr Hansen tells Bill that the reason they can’t return home is because the military have taken over the island to test nuclear weapons. He blackmails Bill, using the secret of the dead baby, to make him dissuade Mill from making the voyage.

Mill tells Bill she is going to use the story of the terrible secret to ensure she is allowed to return to the island. Bill is reminded of how he killed the baby.

Mill tells Mr Hansen the story of what happened on the island during the Second World War. Mr Hansen is affected by the story and promises to help Mill get home to the island.

Bill kills himself because of what he did during the war and because he killed the baby.

Mill prepares to bury Bill and leave for home. Mr Hansen promises he won’t allow them to be forgotten on the island. As the ship is about to leave, Rebecca tells Francis he must choose between England and life on the island with her.