 Adam Thompson thinks one of his nephews, Harry Thompson or Elliott Carter, is rifling the house. He sets up an infrared camera near a wall safe to catch the thief. Adam openly marks a survey map to indicate property that he will soon buy, which his assistant, Ellen Foster, puts in the safe. Unknown to Adam, Frank Jarrett as "Norman Durston," puts up earnest money to buy the precise tract drawn on the map. Adam consults with Perry Mason to find out how the land was sold from under him without the safe having been opened. Adam reveals that he never intended to buy the land, but drew the map as a ruse for the thief. Jarrett, needing money, blackmails Victor Logan over a problem with Logan s credentials. Perry and Paul Drake find Jarrett s body in a running auto in his garage. Later, Harry is discovered rifling Jarrett s office and is arrested for murder. Lydia Logan, Victor s daughter and Harry s fiancée, asks Perry to defend them both.