Geronimo's sister Thea Stilton narrates this tale packed with action, mystery and friendship! When the Thea Sisters' friend Ashvin is in trouble, they rush to his aid. In India! Ashvin has been bringing the monkeys that live in the big city back to their natural jungle environment, but the monkeys have suddenly started stealing jewels! Someone must be behind this terrible theft. Can the Thea Sisters solve the mystery?