Margaret Schlegel reads a series of letters from her sister, Helen, who is visiting the Wilcox family at their home, an old farmhouse called Howards End. Helen writes that she has fallen in love with Paul Wilcox, despite the great differences between their families—the Schlegels are liberal intellectuals, while the Wilcoxes are generally materialistic, narrow-minded, and unprogressive. When Margaret’s aunt, Juley Munt, hears about Helen’s attachment to Paul, she decides to go down to the Wilcox house and meet them. After she leaves, Margaret receives a telegram from Helen saying that the infatuation is over. Juley bungles her first encounter with the Wilcoxes and Helen is badly embarrassed, but Ruth Wilcox steps in and skillfully settles the crisis.
The Schlegels visit the symphony with Juley and their cousin Frieda Mosebach. Helen leaves early and accidentally takes an umbrella that belongs to Leonard Bast, a poor man who couldn’t afford to replace it. Margaret invites Leonard to retrieve his umbrella from their house after the symphony, and he accompanies her home. He envies her superior grasp of art and culture, which he studies in his limited free time. Margaret and Helen pity his hardship. Leonard refuses tea with the Schlegels and returns home to his cramped basement apartment, where he lives with Jacky, a fallen woman whom he has promised to support and marry.
The Schlegels discover that the Wilcoxes have moved to London after the wedding of Charles and Dolly Wilcox. Margaret gradually befriends Ruth, despite their different ages and ideas about life. Ruth suddenly passes away and leaves a handwritten note willing Howards End to Margaret. Ruth’s husband, Henry, and their children disregard her note and say nothing to Margaret about her inheritance.
Two years later, the Schlegels are forced to look for a new house in London. Leonard reenters their lives when he impulsively stays out all night walking and Jacky calls on the Schlegels to look for him. Margaret and Helen are impressed by Leonard’s journey into nature and wish they could do more for him. The next time they run into Henry Wilcox, he tells them that the insurance company where Leonard works may go out of business. The Schlegels invite Leonard over and tell him the news, encouraging him to move companies before he loses his job. Leonard is embarrassed by their concern for his circumstances and reacts poorly, but ultimately takes their advice.
Henry offers to help Margaret find a new house. Spending more time together, they develop romantic feelings and become engaged. Helen objects to the engagement, doubting that it’s a good match, as does Henry’s son Charles, suspecting Margaret of plotting to obtain Howards End. When Henry takes Margaret to see Howards End for the first time, she admires its simplicity and proximity to nature, but Henry considers the house too small and doesn’t intend to move back. He buys a country manor in Oniton, far west of London, where his daughter, Evie, will soon have her wedding.
Margaret travels with the wedding party to Oniton and chafes at the group’s traditional expectations of her in her new role as Henry’s fiancée. Evie’s wedding runs like clockwork until Helen arrives with Leonard and Jacky, intending to confront Henry over his bad advice that caused Leonard to leave his job for nothing. Margaret is upset at her sister for crashing the wedding but agrees to ask Henry to give Leonard a job in his company. Henry, however, recognizes Jacky as his former mistress and refuses to help the Basts. In shock, Margaret tells Helen that she must forget about saving the Basts. Distraught, Helen sleeps with Leonard at the hotel. Later she visits her brother, Tibby, at Oxford and asks him to send money to the Basts for her. She leaves England to avoid her sister. Margaret marries Henry and begins to worry when her sister doesn’t return to England after many months. She shares her fears with Henry, who plots to lure Helen to Howards End, where Ruth’s old friend Miss Avery has somehow unpacked all the Schlegels’ belongings. When Margaret confronts her sister at Howards End, she realizes that Helen has been hiding the fact that she’s pregnant with Leonard’s baby.
Helen plans to return to Germany and raise the baby there. She spends one last night in Howards End with Margaret, much to Henry’s displeasure. The Wilcoxes are scandalized by Helen’s unmarried pregnancy, and Henry refuses to recognize the double standard by which he justifies his own affair but denounces Helen’s. Charles shows up at Howards End the next morning to confront Helen. Leonard also shows up to apologize to Margaret for his conduct with Helen. Charles attacks Leonard on sight to avenge his family’s scandal, and Leonard goes into fatal cardiac arrest. Charles is consequently convicted of manslaughter and sentenced to three years in prison. Henry is crushed by his son’s downfall, and Margaret steps in to rebuild the family. Henry, Margaret, Helen, and her baby move into Howards End. Henry finally gives Margaret ownership of Howards End, like Ruth always wanted, and Margaret plans to leave the house to her nephew when she dies. Leonard may be dead, but his son will inherit Howards End.