 But late at night, they are boarded by local police and plain-clothes men claiming to be customs officers seeking information on stolen chemicals.After the search and their departure, he finds the boat’s well-concealed powerful radio to have been sabotaged.While searching the surrounding area in a Fleet Air Arm Helicopter, Calvert meets the occupants of a castle, Lord Kirkside and his teenage daughter Susan, who both clearly want him away well from the castle, and a fierce gun-toting local on his private island.