During the summer holidays, Milton goes on an unforgettable trip to the Lonely Island. Usually Milton explores nature only in his computer games: he becomes either a brave Sea Hawk or a brave natural scientist who overcomes dangers at every turn, but this time he has to spend the summer without gadgets. While visiting his uncle on the island, Milton realizes that this is his chance to become the brave and brilliant naturalist he always wanted to be, for real, and even meet some other explorers, make friends and help preserve the island.