Peripety is a sudden turn of events in a literary work.  This can certainly be applied to the study of drama, as there are many plays containing peripety.  For example, in "A Raisin in the Sun" by Lorraine Hansberry, Walter Lee Younger makes many mistakes that damage his family both financially and emotionally.  By the end of the play, he has lost all their money and is about to practically sell his soul to a racist representative of the all-white neighborhood that is trying to keep his African-American family out.  However, right at the moment when Walter is about to strike a deal with this man, there is a dramatic instance of peripety.  This sudden turn of events occurs as Walter looks at his son and finally realizes the impact he is having on his family.  He then instantly decides not to bargain with the racist, saving his family from emotional turmoil and assisting them in moving into a better neighborhood and on with their futures.