On Valentine's Day, four members of the Coverdale family were murdered in the space of fifteen minutes. Their housekeeper, Eunice Parchman, shot them one by one in the blue light of a televised performance of Don Giovanni. When the police arrest Miss Parchman two weeks later, they discover a second tragedy: the key to the Valentine's Day massacre, a private humiliation Eunice Parchman has guarded all her life.