Harry spends an adventurous three weeks at his grandfather's house. Strange things begin to happen, including sounds in the night, mysterious intruders, and the finding of hidden staircase. All this leads to the surprising climax and the finding of a precious gem.
Orton began writing at 48 when her children had grown up and her love of history and historical research informed many of her books. Her goal was to include history in the lives of ordinary people so her books often featured historical mysteries. She lived much of her life in the New York City area.