In the year 1258, an old parchment leads two boys onto a perilous trail: Wilhelm Urner, the son of a farmer, and Walter von Wolfenschießen, born of noble blood, uncover the secret of a lost Kyburg treasure. Together with Judith ab Dorf, they embark on a daring adventure just as the feud with the Gruoba knights threatens the valley of Uri. Between the tower of Bürglen, a mysterious isle on Lake Uri, and a hidden cave at Diegisbalm, friendship, loyalty, and courage are put to the test. What begins as a quest for gold becomes a trial of spirit that will change their lives and the fate of their land forever.