Act 1

Strange Interlude begins in August, 1919, in the library of Professor Leeds's home in New England. Marsden has just returned from World War I in Europe, although he did not serve in the military. He and Leeds discuss Leeds's daughter, Nina, who has had a nervous breakdown following the death of her boyfriend, Gordon, in the war. Leeds believes that Nina has turned against him because he persuaded Gordon to postpone their marriage until Gordon had safely returned from the war. Nina informs her father that she intends to work as a nurse at a sanatorium for wounded soldiers. She still grieves for Gordon and feels this is her duty. Leeds opposes her wish and confesses that he was jealous of Gordon because he wanted to keep Nina's love for himself. But he finally agrees to let Nina go.

Act 2

A year later, Leeds has just died and...