This play is by Langston Hughes, and the entire title is Mulatto: A Play of the Deep South. From the title, you might surmise that there will not be a happy ending. Here is the summary:
Act 1: The play opens on Colonel Thomas Norwood's Georgia plantation. We learn his wife has died, and Norwood lives on the plantation with Cora, his black housewife, and their mulatto children. Several of their children are light skinned enough to pass as white. In fact, his oldest girls are going to school to learn typing although Norwood thinks they are learning cooking and sewing. They are preparing for more pleasant and lucrative lives as educated light-skinned negroes who can pass as white than intending to admit their entire heritage. However, Robert, one of Norwood's mulatto sons, begins thinking of himself as "Mr. Norwood" and more important than he should during this time period. He is causing problems at the post office and calling himself Norwood's son in public, causing problems for Norwood and for all the slaves on the plantation.
Act 2, scene 1: Robert has taken his sister Sallie to the train to go to school. Norwood has asked Cora to send Robert to him when he returns. Cora gets Robert to agree with anything Norwood says to him, which Robert says he will unless Norwood tries to beat him. When they meet, Norwood tells Robert that he will address him as an African American should. Robert says he is Norwood's son, and Norwood says Robert has no father. The two fight, and Robert strangles Norwood to death. Cora tells Robert to run to the swamps, and as he exits, he runs into two white men who are coming to see Norwood. They give chase. Cora, meanwhile, continues to talk to Norwood as if he were living. She tells him to get up off the floor and stop pretending to be dead. It is clear that she has lost her marbles.
Act 2, scene 2: With Norwood dead, the slaves realize that they are free since there are no other white masters on the plantation. Everyone but Cora runs off. The undertaker shows interest in Cora, but understands that she is now crazy, so he leaves without her. Robert returns from the swamp with only one bullet left in his gun. He has saved it for himself, and shoots himself before the white men can come back and hang him for murdering Norwood.