我和我的家人被邀请去葡萄牙的里斯本，去追溯伟大探险家Vasco da Gama的旅途。他是**个通过海洋航行到达印度的欧洲人，显然他是Stiltons的祖先！可是我们一上船，就有人捣乱！我能找出是谁吗？

My family and I, Geronimo Stilton, were invited to Lisbon, Portugal, to retrace the journey of the great explorer Vasco da Gama. He was the first European to reach India by sea -- and was apparently an ancestor of the Stiltons! But once we got on the boat, I learned that someone was trying to sabotage the voyage. Could I figure out who?