In the opening act of 'An Inspector Calls,' the Birling family gathers to celebrate Sheila and Gerald's engagement. The atmosphere is one of superficial cheerfulness, which quickly shifts as the mysterious Inspector arrives, initiating a series of interrogations. Priestley uses lighting, stage directions, and dialogue to build tension. For example, the Inspector's entrance is marked by a change in tone and a deliberate pause, creating suspense. The play is set in 1912, just before World War I, but was written in 1945, reflecting on social responsibility. The characters’ dialogues reveal their attitudes, with Mrs. Birling showing snobbery, Mr. Birling emphasizing individualism, and Sheila beginning to question her own morality. Key phrases such as 'fire and blood and anguish' and 'massiveness, purposefulness' highlight the play’s themes of social change and responsibility. Priestley's use of dramatic irony and symbolism underpins the play’s critique of the upper class and their neglect of societal duty.