While out treasure-hunting, Fred stubs his toe on a metal bucket buried in the earth, but what is it? They decide to stick it in the Treasure Truck and head off to the Museum of Cornish Treasures. Suzy identifies it as a bucket made of tin, an important metal in the history of Cornwall. Archie the robot gives them a clue that the secret of their treasure can be found where people once dug underground. Connecting the two, Suzy sends Fred and Pete off to the tin mines. Jack, the manager of Geevor Tin Mine, gives Fred and Pete an underground tour and explains that tin was mined in Cornwall for thousands of years and used to make all sorts of objects. The boys show him their treasure, which he identifies as a tin miner’s lunchbox.

Jack points out that tin miners had very dirty hands, meaning they needed a special kind of lunch in their lunchbox. What could that be? Jack gives them a clue – the words ‘oggie, oggie, oggie!’ Suzy gets in contact via the Treasure Comm and explains that an oggie is an old word for a Cornish pasty. She sends Fred and Pete off to meet pasty chef Matt. Matt shows the boys the ingredients that go into a pasty and helps them make their own. He points out that the big crust was made for miners' dirty hands to hold on to and that the pasty fits perfectly in their tin bucket. They make their pasties just in time to feed the staff back at Geevor. However, when they get there, the pasties are stone cold! Jack comes to the rescue and points out that the tin bucket can be used to warm up them up. Fred and Pete take the bucket back for Suzy to display in the museum. Show less