When Oliver goes to stay with his grandparents on Herald Island, he discovers what he thinks is an old shipwreck in the Upper Waitemata Harbour. When they do some online research, Oliver and his grandfather discover the shipwreck is actually an old World War II airplane, a Hudson. They try to have a closer look at the wreck in Gramps' tinny, but they just can't manage to reach it. Desperate to reach the plane, Oliver 'borrows' a kayak without telling anyone. He manages to reach the wreck, but his inexperience of tides and currents leads to near disaster and he becomes stuck in the mud with no-one knowing his whereabouts. Can Molly, the family's faithful labradoodle, save the day?