Aside from his prowess in forming convincing and disturbing plots, O'Neill demonstrates his dramatic prowess in the way he works with language itself. Even more impressive is that he is able to do this not in a high-flown, abstract language, but through the mouth of the most uneducated and most subtlety-averse character: Yank. Since the idea of thinking is introduced ironically, it makes a special and unmissable impression upon his fellow workers and the audience when, after his encounter with Mildred, he repeats the same phrase with sincerity. The stage directions mention specifically that the workers notice and are confused by this reversal.
It is about a beastly, unthinking laborer known as Yank, the protagonist of the play, as he searches for a sense of belonging in a world controlled by the rich. At first, Yank feels secure as he stokes the engines of an ocean liner, and is highly confident in his physical power over the ship's engines and his men. However, when the rich daughter of an industrialist in the steel business refers to him as a "filthy beast", Yank undergoes a crisis of identity and so starts his mental and physical deterioration. He leaves the ship and wanders into Manhattan , only to find he does not belong anywhere—neither with the socialites on Fifth Avenue , nor with the labor organizers on the waterfront. In a fight for social belonging, Yank's mental state disintegrates into animalistic, and in the end he is defeated by an ape in which Yank's character has been reflected. The Hairy Ape is a portrayal of the impact industrialization and social class has on the dynamic character Yank.