It seemed to be just another so-called "adventure cruise" among the tropical islands of the Indian Ocean. The "adventure" being little more than the delivery of mail and stores by Captain Cassidy's coaster, Sunglow. But this was to be a very different cruise. Cyclones are almost unheard of in those seas in September, yet one engulfed the decrepit little coaster and tested passengers and crew. Treasure hunts for missing gold inspire scepticism, yet the chart left by Mrs Clutterbutt's great-grandfather seemed convincing. Was it one of Sunglow's apparently humdrum passengers who drove the knife into the jugular vein of the mysterious Dada? And the passengers lost overboard in the night. Was it accident, suicide, or something more sinister?