The Legend of the Lost Gold — Carolyn Keene

Nancy, Bess, and George are vacationing in beautiful Big Sur on the rugged California coastline. But soon after they check into the Opa Tourist Lodge, their cottage is ransacked, and Nancy makes a startling discovery: The popular tourist retreat is also a hotbed of deception and crime!

Her investigation leads from the magnificent Caine Castle straight to the heart of a dark mystery. Deep underground lies a labyrinth of caves -- the site, according to rumor, of a treasure in gold. But someone wants the truth behind the legend to stay buried forever, and the deeper Nancy digs, the more perilous her search becomes!