She would fill her pockets with key limes and gather them in her skirt. Scarpetta made key limeade and pies, and everybody felt just a little bit better. She carried key limes to her neighbors when she was hurting, lonely, and sad. Her family had just the one tree, and Scarpetta thought of it as hers. It began to die when she was in her late teens, and she consulted a number of greenhouses, horticulturists, the Department of Agriculture, and even a plant pathologist at Cornell, where she spent her undergraduate years. There was a citrus canker, she was told. It was wiping out thousands of key lime trees in south Florida.

She doused her tree with micronutrient spray and cleaned out the dead wood. She made certain the roots weren't being damaged by the lawn mower or the trunk wasn't being rotted by standing water. Her tree continued its decline, lesions in the stems, leaves turning yellow and drifting to the grass. Scarpetta's tree died long before she gave up on it. She would not let her mother cut it down.

These days, not surprisingly, key limes are very difficult to find, thus making the dessert all the more rare and wonderful. Scarpetta gets her limes from Florida Keys Key Lime Products by making generous donations to the Marine Resource Development Foundation, in hopes that science might yet save the precious fruit. She usually orders half a bushel a month and freezes the juice, which is why she happened to have some on hand the day after Christmas when she entertained Marino and Lucy. Scarpetta thawed half a cup, which also included a hint of grated rind.

Her crust is a very basic mixture of two cups of all-purpose flour kneaded with two-thirds of a cup of softened butter. Sprinkle a little water and spread the dough paper-thin in a pie pan. Bake until a light golden brown.

Mix the key lime juice with one can of Eagle Brand condensed milk (it works as well as anything made from scratch).