In the little town of Vevey, Switzerland, Winterbourne, a young American gentleman, vacationed at the Trois Couronnes hotel, the nicest of the hotels bordering Lake Geneva. Toward the end of June, many American tourists descended upon the town. Winterbourne had lived in Geneva since he was a boy and attended college there. It was rumored that he was devoted to an older woman which kept him in Geneva. He had come to Vevey in order to visit his aunt but she was indisposed one evening with a headache, which was not unexpected.
Winterbourne retired to the garden for coffee and a cigarette. A small boy came upon him with a long alpenstock. The boy asked Winterbourne for his extra sugar which Winterbourne gave him disapprovingly. The boy's word choice and accent confirmed to Winterbourne that he was American. The boy proclaimed that American candy was the best and he and Winterbourne jokingly declared that American boys and men were the best. The boy's strikingly pretty older sister approached and reprimanded her brother, Randolph, for kicking up gravel. Randolph told his sister that Winterbourne was American and Winterbourne figured this was a good enough introduction to present himself to the girl. She responded indifferently. Winterbourne pointed to interesting sights in view and the girl paid more attention. He realized that she was not embarrassed but direct and unaffected. Her beautiful face was delicate though slightly unfinished and he figured that she may be a coquette. She told Winterbourne about her family and their travels.
She, her mother, and Randolph were traveling to Rome for the winter. They came from Schenectady, New York where her father was a wealthy businessman. Randolph told Winterbourne that the girl's name was Annie P. Miller though they called her Daisy. Daisy explained to Winterbourne that Randolph wanted to go back home. She talked like she was Winterbourne's old friend. Her manner though was uncultivated and she bragged about the many gentleman she knew in New York. Winterbourne could not decide whether she was simply innocent or designing. She must be a flirt. Daisy asked Winterbourne if he had been to "the old castle", the Château de Chillon. Her brother did not want to go so her mother and she would not be able to either. Winterbourne commented that he would take her and her mother. He was pleased when she replied that her mother would likely prefer to stay at the hotel. When Eugenio the pretentious courier arrived to inform the children of lunch, Daisy informed him that she would get to the old castle after all. Winterbourne told Daisy he would introduce her to someone who could vouch for him.
Winterbourne asked his aunt, Mrs. Costello, if she had noticed the Miller family. She replied that she tried to avoid them. Mrs. Costello was a widow of wealth and distinction. She claimed that she would have made quite an impression upon the world if it had not been for her headaches. Her tone intimated to Winterbourne that Daisy Miller was one of lower social status, a commoner. She was abhorred that the Millers treated their courier like a family friend. Winterbourne said that he had promised to introduce her to his aunt. Mrs. Costello thought Daisy dreadful and declined to meet her. Winterbourne began to doubt. His aunt scolded him for being too innocent because he had been out of America for so long. Winterbourne responded that he was not so innocent.
That night, Winterbourne ran into her. She was alone looking beautiful. She had been walking with her mother but that her mother was trying to get Randolph to bed. Daisy told Winterbourne that she much wished to know such an exclusive woman as his aunt. Winterbourne tried to use the headaches as an excuse but Daisy soon realized the truth. She told Winterbourne not be afraid. Winterbourne hoped he would have to comfort Daisy but upon seeing her mother, his tone changed. Daisy's mother was timid in his presence as she did not normally spend time with Daisy's gentlemen. Daisy notified her mother that Winterbourne would take her to the castle. Mrs. Miller was a silent for a time and then responded that they had wanted to go for awhile. As they spoke, Daisy skipped ahead finally telling Winterbourne to take her on a boat ride immediately. He happily agreed. Mrs. Miller hoped Eugenio would talk Daisy out of going but Eugenio sneered at the idea and told her to do as she liked. He mentioned that Randolph had gone to bed. Mrs. Miller declared to Daisy that now they could go, and Daisy lightly told Winterbourne that their trip was off, leaving Winterbourne puzzled.
Two days later, Daisy and Winterbourne went to Chillon. Winterbourne felt as some romantic encounter was beginning. He had feared she would be an embarrassment but she gave insightful, objective observations on the steamer and looked very pretty. She did disappoint him though. This venture with him did not make Daisy excited or fluttered. To Daisy, Winterbourne seemed grave. He felt like he was smiling largely.
At the castle, Winterbourne and Daisy were mostly alone. He provided her with detailed histories which interested her little. She asked him for details of his life and told Winterbourne about her own. The news that he would be returning to Geneva shortly greatly dismayed her and she ridiculed him. Finally Daisy made him promise to visit in Rome over the winter. He agreed as he was supposed to visit his aunt there. When Winterbourne returned to his aunt, Mrs. Costello shuddered at the thought of such a girl.
Winterbourne came to Rome in January. His aunt had sent him letters commenting the Millers. Daisy was rather intimate with several "third-rate Italians." Winterbourne continued to believe that the family was simply ignorant. Winterbourne was slightly hurt by the news of Daisy's gentlemen so he called first upon an American woman whom he had known for years, Mrs. Walker. Shortly after he arrived, the Miller family arrived as well. Daisy criticized Winterbourne for not coming to see her and then spoke with Mrs. Walker. Winterbourne asked Mrs. Miller how she enjoyed Rome. It had not pleased her like other cities though Daisy enjoyed the society. Daisy again reprimanded Winterbourne for being mean. Winterbourne thought how he made a sacrifice by not stopping in Florence and Bologna.
Daisy asked if she could invite her friend, Mr. Giovanelli, to Mrs. Walker's party. Mrs. Walker agreed. Mrs. Miller mentioned it was time to return to the hotel but Daisy said she was going for a walk to the Pincio. Mrs. Walker did not think it was safe for her to walk alone. Mrs. Miller agreed, noting that she could catch the fever. Daisy told them she would be with Mr. Giovanelli. Still, Mrs. Walker advised her to not be impudent so she decided to walk with Winterbourne. With all of the late afternoon traffic, it took awhile. Winterbourne noticed the attention pretty Daisy received and thought her silly for thinking she could walk alone. Winterbourne said he would not help her find Giovanelli. Daisy told him that she would not allow anyone to dictate her affairs. Winterbourne noticed instantly that Giovanelli was a very good imitation but not a gentleman. Daisy could not tell the difference. Winterbourne wondered if a nice girl would be so ignorant. Daisy made a smooth introduction between the two men.
A carriage pulled up and Mrs. Walker beckoned to Winterbourne. She told him how fifty people had noticed Daisy and she had better save Daisy herself. Winterbourne told her she was overreacting but brought Daisy over. Mrs. Walker asked her to enter the carriage but Daisy declined. She was not five years old. When Mrs. Walker told her she was old enough to be talked about, Daisy told her she did not wish to know what that meant. Finally Daisy asked Winterbourne if she should go. He hesitated but answered yes. She told them to give up on her and left with Giovanelli.
Mrs. Walker demanded Winterbourne get in the carriage. He was critical of Mrs. Walker. Mrs. Walker retorted that Daisy had gone too far in Rome. Winterbourne insisted that she was simply uncultivated. Mrs. Walker wanted Winterbourne to stop his relations with Daisy but Winterbourne refused. Winterbourne exited the carriage. He saw Daisy and her companion sitting together very intimately. Winterbourne walked to his aunt's residence.
At Mrs. Walker's party, Mrs. Miller arrived alone because Daisy and Giovanelli remained at the hotel. Mrs. Walker noted to Winterbourne that she would not speak to Daisy. It was after eleven when the couple arrived. Daisy explained to Mrs. Walker that they had been practicing at the piano so that Giovanelli could sing at the party. As Giovanelli sang, Daisy loudly told Winterbourne that she would not want to dance with such a stiff man as he. She asked about his ride with Mrs. Walker. Winterbourne said he had wished to continue walking with Daisy. Daisy commented on Mrs. Walker's coldness that day. Winterbourne retorted that Giovanelli should have known better. Daisy replied that she refused to change her habits. When Winterbourne called Daisy a flirt, she agreed. Winterbourne explained that Italians took flirting more seriously. Daisy said she and Giovanelli were too close to flirt. Daisy was humiliated when Winterbourne intimated that they were in love. She had not previously minded his frankness. Daisy spent the rest of the evening with Giovanelli.
Mrs. Walker blatantly ignored Mrs. Miller as Mrs. Miller thanked her upon leaving the party. Daisy was deeply offended. Mrs. Walker told Winterbourne that she would never allow Daisy in her home again so Winterbourne went frequently to the Miller's hotel. Giovanelli was usually alone with Daisy yet Daisy was never upset about the intrusion. Winterbourne began to think that she would become a shallow person. A number of Mrs. Costello's friends gathered during the vesper-service at St. Peter's and gossiped that Daisy had gone too far. Winterbourne was displeased but agreed. He pitied Daisy and hoped to warn Mrs. Miller. However, Mrs. Miller's ignorance so stunned Winterbourne that he could not. He did not see Daisy much after that. The Americans hoped to show that Daisy's behavior was not representative. When Winterbourne did see Daisy, Daisy knew he thought that she was too much with Giovanelli. Winterbourne alerted her to the feelings of his compatriots. Daisy realized that she had been treated coldly. He told her how her mother said she was engaged. To upset Winterbourne, she confirmed the rumor. When he believed her, she denied it.
A week later, Winterbourne was inside the Colosseum at night when he noticed Daisy and Giovanelli. Winterbourne now knew that Daisy did not deserve his respect. He turned to leave when Daisy cried out that Winterbourne was ignoring her. Walking to her, Winterbourne scolded Daisy because she was asking for Roman fever. Giovanelli claimed that he was not worried for himself. Daisy said Eugenio could always give her pills. Winterbourne laughed. When she asked about the other day, Winterbourne said that it did not matter whether he thought she was engaged or not. Leaving, Daisy cried to Winterbourne that she did not care if she got Roman fever.
Daisy became seriously ill with fever. Winterbourne visited regularly. Mrs. Miller was surprisingly an efficient nurse. She told Winterbourne how Daisy asked her mother three times to tell him that she was not engaged. Mrs. Miller was pleased since Giovanelli had not bothered to visit during Daisy's illness. Shortly after, Daisy died. Many more visitors attended her grave than expected. Giovanelli told Winterbourne that Daisy was the most innocent. Winterbourne was hurt. Why did Giovanelli take her to the fatal night spot? Giovanelli answered meekly. He also told Winterbourne that Daisy never would have married him. Winterbourne visited his aunt in Vevey the next summer and mentioned to her that he had done Daisy an injustice. He had been too long out of America. Nonetheless, he returned to live in Geneva.