[citation needed] Set in Wales during the early 19th century, the book follows the adventures of Owen Hughes, a young boy who stumbles upon a secret plot involving smugglers, spies, and a hidden treasure.

Owen lives in a small village near the Whispering Mountain, a place rumored to possess magical powers and to be the home of ancient giants.

When Owen discovers an old manuscript that reveals the location of a lost Welsh king's treasure, he becomes entangled in a dangerous quest.

As Owen and his friends delve deeper into the mystery, they face numerous obstacles and adversaries, including treacherous journeys, encounters with mystical creatures, and the constant threat of betrayal.

The young protagonist must use his wits, bravery, and the help of his companions to navigate the perilous Welsh landscape and outsmart those who seek the treasure for their own nefarious purposes.