For a big, bloody, brilliantly plotted novel of World War II espionage I salute Normandie Triangle by Justin Scott (Arbor House: $13.95). The Otter, fabled Nazi saboteur, has put the Normandie on the bottom of New York's harbor. His next target--the Queen Mary, thus to cripple the flow of U. S. troops to Europe. His chief opponents are an exquisite British woman and a young American naval architect.