Chapter 1: The Benefactress
* Harriet Vane, a renowned mystery novelist, agrees to investigate poisoning allegations at Shrewsbury College, an all-female institution.
* She meets the stern Warden, Helen Reed, and learns of the "Gaudy Night" tradition, a centuries-old festival where alumnae return to the college.
Chapter 2: The Poisoned Party
* A party is held for the visiting alumnae, but it is interrupted by the death of Catherine "Cathy" Keeling, poisoned by aconite.
* Harriet and her friend, Superintendent Battle, begin their investigation, interviewing potential suspects.
Chapter 3: The Suspects
* Harriet interviews the members of the college, including the Bursar, the Chaplains, and the alumnae.
* She uncovers a web of relationships, rivalries, and secrets that could lead to the killer's motive.
Chapter 4: The Poison Bottle
* A poison bottle, identical to the one used to kill Cathy, is found in the warden's office.
* Harriet suspects that the warden may be involved, but she lacks concrete evidence.
Chapter 5: The Gaudy Night
* Gaudy Night arrives, and alumnae from around the country gather at the college.
* Amidst the festivities, Harriet continues her investigation, scrutinizing the guests and searching for clues.
Chapter 6: The Poison Pen
* Harriet receives anonymous letters that accuse her of being in love with Superintendent Battle.
* She realizes that the letters are intended to distract her from her investigation.
Chapter 7: The Unmasking
* Harriet confronts the warden, accusing her of being the poisoner.
* The warden breaks down and confesses, revealing that she killed Cathy out of jealousy and to protect another member of the college.
Chapter 8: The Motive
* The warden reveals that she is in love with the college physician, Dr. Thomas Griffith.
* She believes that Cathy was blackmailing Griffith with an affair that he had had with a former student.
Chapter 9: The Resolution
* Superintendent Battle arrests the warden for murder.
* Harriet and Superintendent Battle discuss the case, realizing that they have both been in love with each other all along.
Real Example: Chapter 3 - The Suspects
Harriet interviews various members of the college, including the Bursar, Miss Elspeth McGillicuddy. McGillicuddy is a stern and practical woman who has been at the college for many years. She is fiercely loyal to the institution and its traditions.
During Harriet's conversation with McGillicuddy, she notices several details that raise her suspicions. First, McGillicuddy is strangely evasive about her whereabouts on the night of Cathy's death. Second, she seems to have a personal grudge against Cathy, referring to her as "that meddling girl." Third, Harriet learns that McGillicuddy is in charge of distributing the keys to the college, including the key to the warden's office where the poison bottle was found.
Based on these observations, Harriet suspects that McGillicuddy may have been involved in Cathy's murder. However, she lacks concrete evidence and must continue her investigation to uncover the truth.
