Complex sentence: The main character, an American, named "Frankie," who affects the mannerisms of Frank Sinatra and who has links to the island from serving there during World War II, returns reluctantly when his ship anchors there during a hurricane.
Split into simpler sentences: The main character is an American named "Frankie" who affects the mannerisms of Frank Sinatra. Frankie has links to the island from serving there during World War II. He revisits reluctantly when his ship anchors there during a hurricane.