Hans Castorp is a young man ready to start a career in shipbuilding - but before he does, he decides to visit his cousin Joachim, a patient residing at a tuberculosis sanatorium in the mountains of Switzerland. Castorp enjoys meeting and chatting with the wide array of colorful personalities living at the sanatorium, until its director delivers some bad news: Castorp, too, has symptoms of disease, and must remain at the sanatorium indefinitely. Thus begins a black comedy spanning years, in which he lives and learns in this self-contained world in the mountains.
The Magic Mountain is a bildungsroman and an allegory of the years surrounding World War I, in which Castorp, a naive blank slate symbolizing the Weimar Republic, spends time with the motley crew in the sanatorium, who each represent the nations and ideologies of Europe vying for his attention. World War I broke out and concluded as Mann was writing the novel; at first, he was opposed to the Weimar Republic, but he later changed his mind, and this development in his personal philosophy is reflected in how Castorp and the patients interact over the years, and in Castorp's ultimate fate.
Adding to the novel's staying power are its many layers of allegory and allusion, including Greek mythology, European fable, music, opera, and theater, literature, mysticism, numerology, medicine, and philosophy. Above these layers is Mann's overarching message of illness and death as necessary struggles to overcome before reaching a fulfilled life, a theme from his earlier novella, 'Death in Venice,' that he explicitly wished to revisit and expand upon.