Mr Mentor has invented a machine for finding treasure, and Sunnysands wannabe pirate Horatio Heave Ho can't wait to test it out. He asks Josh, Elsie and two of their friends to join his fearsome crew on a trip to Bongle Island.

Grandpa wants to come too, feeling sure that the invention might need his assistance, but he's not allowed. So he shrinks and stows away on Bob's boat. They set off singing piratey songs and land on Bongle Island. Sure enough, the Fantastible Treasure Finder doesn't work, so Grandpa has to get inside and fix it.

The fearsome crew set off to find treasure, but then the Bonglebirds attack. Not only do they steal their picnic but the shiny key to the engine of Bob's boat too! Everyone is stranded. But luckily, Grandpa hides behind Horatio's stuffed parrot Stinky and scares the birds off. He retrieves the shiny key from their nest and saves the day. Show less