"The Construction In Calais Matter"
Published in The Victor #285-#287, August 6 - August 20, 1966.
British Military Intelligence is very interested in the new facility being readied in the area of Calais. Thinking it was possibly a U-boat station, they decide to send Captain Webb to investigate, knowing his underwater experience would be useful. What he finds, though, is a major site for the German version of the E-boat.