Henry and Zelda find that their favorite teacher, Miss Applebaum, has unexpectedly retired, and they decide to visit her and bring her a begonia. Miss Applebaum is overjoyed to see them, but they are dismayed to discover that she is sick--dying of cancer, in fact.
For the first part of the book, Henry and Zelda visit with Miss Applebaum, and she takes them to Central Park, where she feeds the homeless, and in all things she opens Henry and Zelda to the wonders of the world.
In the second part, Henry and Zelda convince Miss Applebaum to get a second opinion on her condition. She is admitted to a hospital and there she remains, growing sicker and weaker, until the end of the book. During this time, Henry and Zelda continue to visit her, and she conscripts them to fill in her work feeding the homeless.
At last, having had enough with the ineffective treatments, Miss Applebaum checks out of the hospital, and Henry and Zelda take her home, where, after asking Henry and Zelda to keep feeding her homeless friends through the winter, she dies. Following her final request, Henry and Zelda bury her in Central Park, near her favorite bench, by placing her body in a trench which was dug for a new pipe, and covering it so it would not be noticed before the trench was filled in.
The book is written in Henry's and Zelda's voices, the two alternating chapters (which, according to the introduction, they are writing on an Apple II during computer class). It is interesting and, for a YA book, unusually tragic. It is left open whether Henry and Zelda were really right to convince Miss Applebaum to leave her home and spend her final days in the hospital.