The novel begins with a chaotic scene in a Brussels plaza where a runaway pig causes commotion. This incident ties into a larger economic issue for the EU, as China, the largest importer of pork, opts to negotiate with individual EU countries instead of the union. The management of pork within the EU Commission is divided among different directorates (AGRI, GROW, and TRADE), leading to bureaucratic clashes which are heavily satirised. The plot centres on the Directorate-General of Communication’s neglected Culture Department, led by Fenia Xenopoulou. While hoping to secure visibility and praise for a promotion to a department with a better reputation, she passes the task of organising a significant jubilee to celebrate the commission’s 50th anniversary to her assistant, Martin Susman. Martin, an Austrian intellectual and idealist, sees the celebration as an opportunity to highlight the EU's founding principle of "never again" to global conflicts and the Holocaust. He discovers records of Holocaust survivors from a nearby deportation centre, including David de Vriend, now living in a Brussels retirement home. Concurrently, Police Inspector Brunfaut investigates an assassination tied to the pig incident but is ordered to cease his investigation by a higher authority. The narrative also follows his brother, Florian Susman, head of the European Pig Producers, who narrowly escapes death after being run over by a cab driver profiting off disoriented groups of refugees headed to the train station. Florian is rescued by a Muslim woman, creating a poignant image that gains international attention.

Underneath the plot’s immediate surface lies a critical examination of the history of the European Commission, its present relevance and effectiveness, as well as its future under the sign of many crises, brought about by unpopular austerity policies and management of resources, Brexit, permanent tensions between long-term collaboration and short-term national interests, as well as foreign interference (mainly from China). The novel is a rich tapestry of socio-economic entanglements and political intrigue, at both individual and international scales. Among its recurrent concerns are the rise of nationalism, the failures of integration, and the general feeling of disconnect between EU institutions and European citizens. The concept of European identity and the idealistic rhetoric of its institutional self-representation are given centre stage, along with the multiple challenges that call them into question. This exploration of unity, diversity, and belonging within the EU framework underscores the novel's status as a quintessential political narrative.

Die Hauptstadt draws extensive thematic and stylistic parallels with another Austrian novel, Robert Musil’s 1930 The Man Without Qualities. Pointing explicitly and repeatedly to this reference throughout the book, Menasse updates the theme of a large-scale institutional jubilee to the context of contemporary European politics, identity and self-representation. Like its illustrious predecessor, the novel builds a satirical commentary by interweaving multiple storylines and viewpoints whose juxtaposition goes beyond mere humour, well into the depths of the grotesque and the absurd. The book can also be productively compared to other novels whose plot revolves around the European Commission and its workings, such as Jean-Philippe Toussaint’s Les Émotions (2020).

Multilingualism plays a significant role in Die Hauptstadt, whose action is set in a city that naturally blends Flemish, French and German with the institutional English of large-scale international politics. Fragments in Polish are sprinkled throughout, and characters sometimes switch between languages. This strategy underscores the challenges and opportunities that come with Europe’s linguistic diversity, an important factor in its negotiations of various crises, as well as in its everyday operations. It highlights both the potential for miscommunication and the richness that different languages bring to the EU's identity and culture. 

Die Hauptstadt has received the 2017 German Book Prize for being “a novel that contains everything about our era without ever becoming zeitgeisty.” The jury also qualified it as “a unique panoramic view of Europe – criminally driven, steeped in philosophy yet always fundamentally ironic.” Some literary scholars, such as Alexis Radisoglou, consider it the pioneer of an emerging genre: “the EU Novel”. Its recent, longer sequel, Die Erweiterung [The Enlargement], has been awarded the 2023 European Book Prize.