Summer of Fear — Norma Davis Stoyenoff

Julie Adams has a penchant for solving puzzles, but when she arrives on the privately owned Thunder Island to spend the summer working as secretary to rich, elderly T. Richard Landis, she finds herself at the center of a dangerous, real-life jigsaw puzzle. Something strange and frightening in going on, and someone is determined to keep her from finding out about it.

From the moment she sets foot on the island, Julie knows she is being watched, and someone keeps leaving threatening messages. Who is it who is determined to scare her away? Is it Beatrice Troxell, the jealous housekeeper; Louis Gilroy, the menacing valet -- or Brad Cummings, the handsome, intriguing vacationer who tried so hard to prevent her arrival the very first day? This is one puzzle she has to solve -- and quickly. Her life depends on it!