Who acts as the man who breaks his arm?
Bobby, who lives on a farm in an unspecified area of Nebraska with his mother, Glenna, and grandfather (Charles Napier), is a typical eight-year-old boy with an overactive imagination. Often receiving punishment for his make-believe adventures, Bobby believes his imagination to be a negative trait. When Bobby's grandfather falls and breaks his arm due to an approaching storm, Bobby is left on the farm alone while his mother accompanies his grandfather to the hospital.
During this storm, a "vortex in time" is created and deposits "Captain" Jezebel Jack, a self-centered pirate who was forced to walk the plank on his own ship and sent into the vortex. Jack awakes in a field of wheat, where he finds Bobby, who tends to his wounds after he loses consciousness again.
While adapting to the advances of modern technology (such as a television), Jack is told of an old buried treasure map by Bobby, and demands they follow the map. Bobby explains that his grandfather explained to him the story, and that the map is written in some unknown code. Jack says that the map is in "Adventurer's Code", in which he is fluent. The two immediately begin to follow the map, and quickly find the treasure buried under an old tool shed.
Shortly after uncovering the treasure, another vortex in time is opened, and the rest of Jack's mutinied crew is deposited. The crew quickly learn of the treasure, and open attack on Jack and Bobby, who are forced to defend the house and the treasure. After Bobby, who has by now become close friends with Jack, is captured and held in ransom, Jack is forced to hand over what is believed to be the treasure. The boy is released, but Jack is forced to stay with the crew, who are teleported back to their native time.
Charles Napier