Lost in the Secret Cave: A Daring Adventure: Book 10 — Peter Reese Doyle

The tenth book in the exciting Daring Adventures series!

Off the beautiful coast of Portugal, Mark, Penny and David set out to explore the famous ports where, centuries ago, the Portuguese launched voyages seeking trade routes to Asia. While investigating a cave on the side of a rocky cliff, the three find a hidden treasure from a sunken ship -- piles of gold bars! Now the teens find themselves caught in the middle of a smuggling operation, and the enraged criminals wills stop at nothing to protect their stolen fortune.