The Hidden Trail, by Roy J. Snell (epub/Kindle/pdf)
Roy J. Snell authored more than 80 books aimed at teenage boys and girls over his long and prolific career, including the "Mystery Stories for Boys" series and trhe "Mystery Stories for Girls" series. "The Hidden Trail" (1924) is volume 7 in the Mystery Stories for Boys" series and continues the adventures of a team of young amateur sleuths.