The Children's Hour

While Lillian Hellman's The Children's Hour shares several attributes of the Well Made Play, it has a few key differences.  It does have three acts, the plot depends on a secret, there is a long opening exposition, and the plot fits nicely into a Freytag graph.  These are all attributes of Well Made Plays.

While the plot does depends on a secret, it's a secret that is kept from the audience until near the end of the play.  Mrs. Mortar accuses Martha towards the beginning of the play of having "unnatural" feelings towards Karen.  The entire plot surrounds this secret, but we the audience don't actually know that it's actually true until the last scene of the play.  Additionally, the story does not have a "happy, logical resolution."  I'd hardly say that Martha committing suicide as opposed to living life as a lesbian women ties everything up in a neat little bow.