Alerted to the possibility that her family had ties to the slaveholding South, Sylvia searches her attic for her great-grandmother's quilt, a log cabin with black central squares that, according to legend, was a sign of sanctuary to slaves escaping north along the Underground Railroad. In the attic, she also discovers the memoir of her great-grandfather's spinster sister, Gerda Bergstrom, which becomes the catalyst for a journey back through time and memory.