Sartre's No Exit is a play about the "devouring" gaze of others and how it restricts one's freedom. The characters constantly look for mirrors in order to avoid the judging gaze of each other, while their failure is played out by the constant stare of the play's spectators. The play's central themes of freedom and responsibility come from Sartre's doctrine that "existence precedes essence."
Sartre believed that human consciousness, or a "being-for-itself," differed from inanimate objects, or a "being-in-itself," since humans have the ability to choose and define their characteristics. However, this freedom of choice comes with the responsibility for one's action. The fear and anxiety of this responsibility leads many people to ignore both their freedom by letting other people make their choices for them, resulting in bad faith.
This emphasis on bad faith establishes Sartre's underlying argument of the play — "Hell is other people."
Using only three people and an empty room, Sartre evokes scenes of utter torture and despair. As Sartre explained, "Life begins on the other side of despair."