Most plays of the 1950s were three acts, whether comedies or dramas. I find it hard to believe that Shayne has never seen one. Dial 'M' is a perfect example, along with Tea and Sympathy, The Seven Year Itch, Will Success Spoil Rock Hunter (The Bad Seed is a two-act play), A Raisin in the Sun, Bus Stop, Born Yesterday, No Time for Sergeants, and The Rainmaker, to mention a handful off the top of my head.