Previously in Lady Windermere's fan
The ball takes place in the Windermere's house, Lord Darlington tries to convince Lady Windermere to leave her husband and continue her life with him. The guests make their acquaintance with Mrs. Erlynne.
Later that night, when the guests have started to leave, Lady Windermere makes the decision to run away with Lord Darlington. She leaves a note for Lord Windermere explaining what she is going to do. The note is found by Mrs. Erlynne, who immediately goes after Lady Windermere to try and stop her from running away with Lord Darlington. It is revealed that Mrs. Erlynne is actually Lady Windermere's mother.