In her introductory note the author recommends to her readers that ""when you have finished reading this book I want you to sort out in your mind the real history from the 'might-have-been.' This makes a kind of puzzle for you..."" That's expecting a lot of cooperation, especially since the audience will very quickly come to the conclusion that the ""might-have-been"" never would have. The historical part deals with the people who founded the first British settlement in western Australia, and it forms a rather sketchy background to the story. There were military men and their families, and there were convicts, but it is the children on board who manage to save the expedition. They are thirteen year old Robert Morton, and his fourteen year old sister Charlotte. The convicts include some congenial men but there is also the compulsively sinister Snark. Robert discovers that Snark is trying to organize the other convicts to join in with the sealers (who are hostile to the idea of settlement) and overthrow the expedition. And somehow connected with this plot is a stolen diamond necklace Snark has kept hidden. There are many inconsistencies and the events are much too adolescent-directed.