The Famous Five are on an adventure. This time they plan to go on a trek for the half term holidays. Julian plans out the trip and they set off. Crossing meadows they first buy food for the trip. On the trip Timmy hurts himself in his leg so George and Julian take Timmy to Mr. Gaston in the village while Dick and Anne find a place to stay. Soon they get lost and stay in an old woman’s house with her short-tempered son. Soon Dick and Anne get out of the place and find Julian, George and Timmy. They finally move on with a criminal at loose. Meanwhile Dick tells to the others about a man who had come to the barn and told him some words and gave him a letter. Soon the Five go to that place where the man told and find a burnt house. They set up camp in the cellar of the house. They go by the letter in finding the loot from the robberies. They reach the place and enjoy themselves. They are accompanied by Maggie and Dirty Dick, who is the son of the old lady. The five find out that Maggie was a thief partner of Nailer, who stole many jewels and hid them. The Five act like normal kids who have just come for a hike and secretly try to take the loot. Maggie and Dirty Dick steal some of the food. Both Maggie and Dirty dick start to hate them a lot. The Five find the loot in a sunken boat and keep a cork with a weight to mark the place where the sunken boat was when they come the next time. The Five take the treasure at nightfall and find lots of jewels and they go away but Maggie and Dirty Dick find it and chase the Five. The five have no access to civilization as they are too far away. Will the Famous Five escape or get caught? To know the rest of it you have to read the book to find out.