In a great extended flashback, Edna's grandmother has been telling of her World War II adventures as a femme fatale, who fell in love both with a German POW who taught her to sing better, and the American officer who sent her in. The American vanished during the invasion of France, but the Austrian has surface in New York, singing in the opera. The two have found each other and ... clenched hands have resulted.
This is the third example of sexuality that Brooke McEldowney has shown in his strip. Our notes on number one is here and number two is here.