La pietra verde

Gustave Danardière is a sincere friend of the American cause, as was his recently deceased uncle. The man left a map with directions to find a stone of exceptional value to donate to the Revolution. But there is someone else who knows about the stone: Bonanza the adventurer, an unscrupulous man, accompanied by the trusty Indian Xavan. And then the English want to capture young Gustave at any cost. Oh yes: the search for the emerald for Mark and Gustave will be anything but a pleasant walk!