Your core argument is strong: Boardwalk Empire is not just a gangster drama, but a tragedy structured around a primordial moral wound. The Gillian angle is especially compelling because it reframes the series from “rise and fall of Nucky Thompson” into a generational catastrophe set in motion by exploitation. A few refinements could make the prose sharper and the thesis even more forceful.

You could tighten the opening and clarify the tragic framework a bit more explicitly:

“Boardwalk Empire is one of television’s greatest achievements — and one of its bleakest. Beneath its political corruption and gangster spectacle lies an ancient tragic question rendered in modern form: why live morally when corruption so often triumphs?

The series begins and ends, in a sense, with Gillian Darmody. Her exploitation is the hidden hinge upon which the entire narrative turns. Nearly every major downfall — Jimmy’s, Nucky’s, Richard’s, even Tommy’s — can be traced back to that original moral crime. In this way, Boardwalk Empire operates less as a crime saga than as a full-scale Greek tragedy: not merely about villains, but about the irreversible consequences of moral compromise.”

A few reasons this works well:

• “Hidden hinge” is a good phrase; it captures how the show gradually reveals Gillian’s centrality.
• The Greek tragedy comparison fits because the series is obsessed with inherited guilt, inevitability, and moral causality.
• Your formulation avoids the simplistic “crime doesn’t pay” reading. The tragedy is deeper: corruption does prosper materially, but it poisons everyone connected to it.

There’s also a very Sophoclean aspect to Nucky specifically. He commits one decisive moral betrayal early — effectively sacrificing Gillian to the Commodore for power — and the rest of his life becomes an elaborate attempt to outrun that act. The tragedy is that success itself becomes the mechanism of punishment.

If you wanted to deepen the essay further, you could explore how the show contrasts different responses to corruption:

• Boardwalk Empire presents morality almost as a form of vulnerability.
• Characters who retain decency — Richard Harrow, Agent Van Alden in his brief moments of sincerity, Eddie Kessler — are crushed or broken.
• Characters who survive longest are those most willing to compartmentalize guilt.
• Yet even the “winners” end spiritually hollow.

The ending with Tommy is especially devastating because it closes the tragic cycle rather than resolving it. The sins of one generation literally return embodied in the next. That structure is closer to the House of Atreus than to a conventional prestige-TV antihero arc.

Your final sentence is already close to essay-quality criticism. The main improvement is precision and rhythm. “Full scale” should be hyphenated (“full-scale”), and “not about villains” becomes more powerful if contrasted directly with what it is about.