Buying stocks (and solid gold submarines!)

"Deep-sea mining for gold and silver has triggered a chain of dangerous earthquakes, and it's up to Benji Franklin and his fantastic problem solving skills to put an end to the shakeups and save the nearby islands from disaster. Will Benji's super-smarts alone be enough to quiet the underwater tremors, or are some problems too big for even the Kid-Zillionaire?"--Provided by publisher.