Clarissa Dalloway goes around London in the morning, getting ready to host a party that evening. The nice day reminds her of her youth spent in the countryside in Bourton and makes her wonder about her choice of husband; she had married the reliable, successful, Richard Dalloway instead of the enigmatic and demanding Peter Walsh, and she "had not the option" to be with a female romantic interest, Sally Seton. Peter reintroduces these conflicts by paying a visit that morning. Peter's visit made it clear that he was still in love with Clarissa (despite mention of his new love interest: Daisy), and Clarissa expressed her desire for Peter to take her away. Clarissa additionally invites Peter to her party that evening.
Septimus Warren Smith, a First World War veteran suffering from deferred traumatic stress, spends his day in the park with his Italian-born wife Lucrezia. Lucrezia, in turn, experiences major loneliness as a result of her husband's isolating illness. His going to war affected not only his ability to function, but Lucrezia's as well. Septimus is visited by frequent and indecipherable hallucinations, mostly concerning his dear friend Evans who died in the war; he is also unable to feel emotions for anyone, including his wife. Septimus's relationship with doctors: Sir William and Dr. Holmes is extremely poor. He fears for his safety in the presence of both doctors and often questions human nature after their interactions. As a product of his prescription (by the two doctors) of involuntary commitment to a psychiatric hospital, he commits suicide by jumping out of a window.
Clarissa's party in the evening is a slow success. It is attended by most of the characters she has met throughout the book, including people from her past (Sally, Peter, etc.). She hears about Septimus' suicide at the party and gradually comes to admire this stranger's act, which she considers an effort to preserve the purity of his happiness. Clarissa also acknowledges her ability to relate to Septimus, regardless of her limited knowledge of him.
