Clarissa Dalloway, the main character, leaves her house at 10 a.m. to buy flowers for a party she is hosting that evening. While she is out, a car drives by noisily, shifting attention to Septimus and Lucrezia Warren Smith, a married couple walking nearby. Septimus is a World War I veteran suffering from shell shock, and he is under the care of doctors, including the renowned Sir William Bradshaw.
Clarissa returns home and is surprised by a visit from Peter Walsh, a man she once loved. After leaving her, Peter goes to Regent’s Park, where he briefly sees the Warren Smiths heading to their medical appointment. During the interview, Sir William decides Septimus should be sent to one of his clinics.
Later, at 6 p.m., Septimus commits suicide by jumping from a window. As his ambulance passes by, Peter Walsh sees it on his way back to his hotel. That evening, Clarissa’s party takes place, and all key characters from the day are present. She hears about Septimus’s death and feels a deep connection to it.