Hans Castorp, an "ordinary" young German orphan from Hamburg about to begin a dull shipbuilding apprenticeship, visits his tubercular cousin Joachim Ziemssen at the International Sanatorium Berghof in the Swiss Alps in the years before World War I. Hans comes for a stay of three weeks - but ends up staying seven years, after he himself is diagnosed with TB (or is it really love?). With an international clientele, the Berghof is a microcosm of a frivolous, distracted Europe on the eve of cataclysm. The sanatorium's "enchanted" patients amuse themselves with love affairs, fads, and distractions as they await a cure (or death) in a world where time means something very different from time in the "flatlands." Hans Castorp falls hopelessly in love with a fellow patient, and is inspired to plunge into new worlds of study, tugged in different directions by love, idleness, learning, and passion.

Things become more complicated when two self-appointed mentors begin to struggle over Hans' German soul. Lodovico Settembrini is a witty and impassioned writer, activist and Freemason, glowing with Enlightenment ideals that may be as threadbare as the one set of clothes he owns. Leo Naphta is a brilliant, sarcastic Jewish-born Jesuit who combines asceticism and luxury, reverence for the medieval past with communistic and nihilistic ideas about violence and absolute terror. Their arguments lay out the stark choices facing Hans, and by implication, his generation of Germans: West or East. Culture or civilization? Democracy or violence? Hans finally declares himself to his love, the Russian Clavdia Chauchat, only to learn that she is leaving the following day. His cousin Joachim, whom other patients consider the "best of the lot," finally leaves without authorization, to take up the soldier's career he has always wanted, only to be forced to return to die. Joachim's death symbolizes the death of everything good and honorable in the German military tradition. Hans, his ties to his extended family now broken, waits for Clavdia's return. However, when she returns, Clavdia brings an unexpected traveling companion and unforeseen complications. In their wake, Hans abandons himself to the passing years. Eventually, the Berghof patients can no longer ignore currents from the outside world that will wake them from their enchanted sleep, and Hans makes a fatal choice.