I remember reading this book [amazon.com] long ago. It was published in 1984, actually. Well written; would probably be an interesting read now even for a children's book. You might find it at a local library (send the kid in to get it, don't want to scare all the little kids in that section of the library).

It tells pretty much the same story about Captain Kidd, through the eyes of his cat. While no one really knows how far Kidd went, there are enough ambiguities to make this at least one possibility. We probably will never really know...the lure of incredible wealth is certainly very strong.