The play is set in the summer home of the Tyrone family, August 1912. The action begins in the morning, just after breakfast. We learn as the first act unravels that Mary has returned to her family recently after receiving treatment in a sanatorium for morphine addiction. Edmund, meanwhile, has in recent weeks begun to cough very violently, and we learn later on in the play that, as Tyrone and Jamie suspect, he has tuberculosis. Throughout the course of the play, we slowly find out that Mary is still addicted to morphine, much to the disappointment of her family members.