London, 1921. In her elegant Mayfair drawing-room, Joan Loyalty awaits her secret lover, Hugo Carr. For two years they have met in clandestine silence—but now Hugo intends to confess the truth to Joan's husband, Ralph. Before the storm breaks, Joan asks for half an hour's peace, a respite shattered by a tragic message brought by the butler. That very night, in which all involved seek only to shield one another, they fatally miss their mark.
With the metaphorical image of the nightingale filling Mayfair with its song, Arlen transposes the chimera of happy love onto his protagonists.