The clue of the second murder

After leaving his sister's opulent Garden Party in 1927 Greenwich, Connecticut a naval inventor is shot dead while driving his Packard down a country lane beside the estate. Bill Adams, teen sleuth, begins the investigation, calling his friend, Detective Van Dusen Ormsberry home from his vacation in France to prevent an unjust conviction. Ormsberry must wade through the accused's past political scandal; the torrid love triangle of the accused, the stage actress and the victim; and the post-World War I International espionage ring he discovers to find the actual murderer.