What was troubling Johnsy, and how did she get well?

Johnsy was suffering from pneumonia and had mentally given up the will to live. She convinced herself that when the last leaf fell from the ivy vine, she would die too.

• She counted leaves obsessively, watching them fall one by one.
• One leaf stubbornly refused to fall even through storms and Johnsy slowly regained her will to live.
• She began eating and recovered.

The tragic twist: The leaf was not real. The old artist Behrman had painted it on the wall on a stormy night to give Johnsy hope and died of pneumonia himself that night. It was his masterpiece.

Summary: Johnsy lost her will to live during pneumonia, but a painted leaf Behrman's final selfless gift restored her hope and saved her life.