World renowned concert pianist Karen Duncan arrives at Mount Vierge, a Swiss mountain sanitarium, for a rest cure, unaware that her lung illness is terminal.  She soon falls in love with her doctor, Antony Stanton, but his strict enforcement of sanitarium rules causes her to believe he has no heart.

One day while driving into the local village to do some shopping, Karen runs into a roadster belonging to playboy and racecar driver Paul Clermont.  Paul immediately invites Karen to the races and dinner in Monte Carlo.  In town, Karen meets fellow patient Celestine, and together they affirm the exhilaration they feel being freed from the sanitarium.

Later, when Karen explains her "epiphany of wellness" to Tony, he warns her not to return to the village, but to rest.  Furious at Tony's unromantic bedside manner, Karen flees to the village to meet Paul.  After he asks her to run away with him and travel around the world, she returns to the sanitarium for her luggage and learns that Celestine died that evening from a sudden hemorrage.  Frightened for her life, Karen demands the truth about her condition from Tony, who tells her she must become an automaton for a time if she expects to survive.  He also confesses his love, but she does not believe him, and runs to town to meet Paul.

They travel to Monte Carlo in the night, and she spends the ensuing weeks staying up late, drinking, smoking and gambling.  Whenever Karen has a bad coughing spell, she takes a pill, then resumes her fast pace with Paul.  Soon she is feverish and losing weight.  Tony locates them and appeals to Paul to take Karen to a climate that won't kill her.  Later, during a ship party, Paul tells Karen that he spoke to her doctor and is taking her to Egypt.

Embarrassed by his pity, Karen, who has run out of pills, goes to town in the rain.  A croupier recognizes her and tries to molest her, but she pleads for help and gives him a diamond ring from Paul as payment for transportation back to Mount Vierge.  Tony receives her tenderly and places her in intensive care.

Paul soon arrives at the sanitarium, but finding Karen critically ill, leaves her in the doctor's hands.  Later, Tony proposes to Karen, and they marry, taking up residence in his cozy cabin adjacent to the sanitarium.  One day, as snow falls outside, Tony plays a concerto on the piano as a weak Karen listens, dreaming of the day she will be well again.