When Inspector Goole enters the Birling home, he states that his purpose for being there is to question all those present, hoping to obtain information about a young woman, Eva Smith (also known as Daisy Renton), who killed herself by drinking disinfectant.
Initially, Croft and the Birlings don't understand what his investigation has to do with them, but as he questions each person, he exposes how their actions contributed to Eva's death.
Because the group knows at the outset that Eva died by suicide, the belief that it is too late to rectify the situation increases their sense of guilt and makes their self-reflection more poignant.
The inspector reminds them that everyone has a responsibility to care for those around them. While Mr. Birling remains skeptical of the inspector's words, the younger members of the party are determined to change.