For your consideration is a Judy Bolton Mystery "The Vanishing Shadow" a Judy Bolton mystery book was written by Margaret Sutton and published by Grosset & Dunlap, copyright 1964.
Summary: Judy Bolton is resigned to spending several boring weeks at her grandparent's farm near Dry Brook Hollow. Judy's summer suddenly becomes interesting when she overhears some men talking about the Roulsville dam. Judy does not understand the conversation, but the men fear that she does and threaten her. Judy becomes reacquainted with her childhood friend, Pete Dobbs, who gives her a cat that she names Blackberry, and meet the wealthy siblings, Arthur and Lois Farringdon-Pett. As the days pass, Judy learns that the Roulsville dam is cracked and may break during the next rain, which reminds Judy of the conversation that she overhead. The moment of truth finally arrives when a downpour threatens the dam. Judy must rely on her seemingly brother Horace to warn the people of Roulsville of the danger. All Judy can do is hope that the dam holds long enough for Horace to warn the townspeople in time.
172 page hard cover book in good condition with a nice cover, no rips, tears, or writing. .