While Captain Silver outlined his plans to learn how the Indians in the jungles of Ecuador make their mysterious drug, Jerry was mighty uneasy. In fact, the red haired boy who had just joined the crew of the Sea Hound, broke in on the Captain's story with a bold statement that a spy was among those present! Jerry accused the Chinese scholar called Kukai, basing his accusation on the fact that he had seen Kukai make secret entries in a black notebook - and Kukai certainly acted guilty when he found that Jerry had seen him. For a minute, it looked as if Jerry was right - until Kukai produced the book...