Marie Bishkee is unhappy. Her best friend left town, maybe forever, and Marie has no one her own age to play with in the neighborhood.

Then one day, while riding her bike, she discovers a small garden full of leafy green tomato plants. Racing home, she tells her mother that she wants to grow her own tomatoes.

After her mother agrees to let her buy one tomato plant, and her grandmother shows her how to protect it from cutworms, she plants it. And even though her brother tells her it will probably die, Marie insists that it will live! And it does. However, instead of many tomatoes, it produces only one, but what a marvelous tomato it turns out to be.

Find out what happens as Marie's tomato grows and grows and grows. Will her dreams come true? Will this be her best summer ever?