O'Neill's painful view of his own life forms the core of Long Day's Journey Into Night, one of the greatest of all American plays. The Tyrone family (father James, mother Mary, and sons Edmund and Jamie) of the play is a surrogate for O'Neill's own family and, through them, the playwright wrestles with his past demons.

Covering a single day and night, O'Neill's play traces the impact on the family relapse into a drug addiction and younger son Edmund's being institutionalized for consumption. These events reopen old wounds and resentments and initiate a harrowing series of accusations and recriminations that threaten to tear apart the family.