Nausea is the story of Antoine Roquentin, a French writer who is horrified at his own existence. In impressionistic, diary form he ruthlessly catalogues his every feeling and sensation about the world and people around him. His thoughts culminate in a pervasive, overpowering feeling of nausea which "spread at the bottom of the viscous puddle, at the bottom of our time, the time of purple suspenders and broken chair seats; it is made of wide, soft instants, spreading at the edge, like an oil stain."

Roquentin's efforts to try and come to terms with his life, his philosophical and psychological struggles, give Sartre the opportunity to dramatize the tenets of his Existentialist creed.