To the Lighthouse is divided into three sections: “The Window,” “Time Passes,” and “The Lighthouse.” Each section is fragmented into stream-of-consciousness contributions from various narrators.

“The Window” opens just before the start of World War I. Mr. Ramsay and Mrs. Ramsay bring their eight children to their summer home in the Hebrides (a group of islands west of Scotland). Across the bay from their house stands a large lighthouse. Six-year-old James Ramsay wants desperately to go to the lighthouse, and Mrs. Ramsay tells him that they will go the next day if the weather permits. James reacts gleefully, but Mr. Ramsay tells him coldly that the weather looks to be foul. James resents his father and believes that he enjoys being cruel to James and his siblings.

The Ramsays host a number of guests, including the dour Charles Tansley, who admires Mr. Ramsay’s work as a metaphysical philosopher. Also at the house is Lily Briscoe, a young painter who begins a portrait of Mrs. Ramsay. Mrs. Ramsay wants Lily to marry William Bankes, an old friend of the Ramsays, but Lily resolves to remain single. Mrs. Ramsay does manage to arrange another marriage, however, between Paul Rayley and Minta Doyle, two of their acquaintances.

During the course of the afternoon, Paul proposes to Minta, Lily begins her painting, Mrs. Ramsay soothes the resentful James, and Mr. Ramsay frets over his shortcomings as a philosopher, periodically turning to Mrs. Ramsay for comfort. That evening, the Ramsays host a seemingly ill-fated dinner party. Paul and Minta are late returning from their walk on the beach with two of the Ramsays’ children. Lily bristles at outspoken comments made by Charles Tansley, who suggests that women can neither paint nor write. Mr. Ramsay reacts rudely when Augustus Carmichael, a poet, asks for a second plate of soup. As the night draws on, however, these missteps right themselves, and the guests come together to make a memorable evening.

The joy, however, like the party itself, cannot last, and as Mrs. Ramsay leaves her guests in the dining room, she reflects that the event has already slipped into the past. Later, she joins her husband in the parlor. The couple sits quietly together, until Mr. Ramsay’s characteristic insecurities interrupt their peace. He wants his wife to tell him that she loves him. Mrs. Ramsay is not one to make such pronouncements, but she concedes to his point made earlier in the day that the weather will be too rough for a trip to the lighthouse the next day. Mr. Ramsay thus knows that Mrs. Ramsay loves him. Night falls, and one night quickly becomes another.

Time passes more quickly as the novel enters the “Time Passes” segment. War breaks out across Europe. Mrs. Ramsay dies suddenly one night. Andrew Ramsay, her oldest son, is killed in battle, and his sister Prue dies from an illness related to childbirth. The family no longer vacations at its summerhouse, which falls into a state of disrepair. Weeds take over the garden and spiders nest in the house. Ten years pass before the family returns. Mrs. McNab, the housekeeper, employs a few other women to help set the house in order. They rescue the house from oblivion and decay, and everything is in order when Lily Briscoe returns.

In “The Lighthouse” section, time returns to the slow detail of shifting points of view, similar in style to “The Window.” Mr. Ramsay declares that he and James and Cam, one of his daughters, will journey to the lighthouse. On the morning of the voyage, delays throw him into a fit of temper. He appeals to Lily for sympathy, but, unlike Mrs. Ramsay, she is unable to provide him with what he needs. The Ramsays set off, and Lily takes her place on the lawn, determined to complete a painting she started but abandoned on her last visit. James and Cam bristle at their father’s blustery behavior and are embarrassed by his constant self-pity. Still, as the boat reaches its destination, the children feel a fondness for him. Even James, whose skill as a sailor Mr. Ramsay praises, experiences a moment of connection with his father, though James so willfully resents him. Across the bay, Lily puts the finishing touch on her painting. She makes a definitive stroke on the canvas and puts her brush down, finally having achieved her vision.