Adventure is afoot in the small coastal town of Emerald Cove. Dave Shipper (John Weisbarth) is all set to enjoy a quiet summer, but the arrival of his cousin Jon (Frank Jimison) throws a wrench in his plans. Rather by chance, they happen upon an old map that sets them on a quest, along with Dave's friend Freddy (Freddy Rible), to seek out a legendary treasure said to be buried deep inside the ocean cliffs. With the help of an old local fisherman ("Smokey" Tom Hodgins), the boys compile clues that unravel a 30-year-old murder mystery and lead them closer to their prize. They quickly draw the attention of a bumbling crew of malicious treasure-hunters and a mysterious pickaxe-wielding "digger", all intent on capturing the gold for themselves.