Wikipedia
Nalacharitham is a Kathakali play ( Aattakatha) written by Unnayi Warrier. Based on the Mahabharatha, it tells the story of King Nalan and his consort Damayanthi. The play consists of four parts, each one long enough to be performed over a full night.
The substance of the story of Nalan and Damayanthi is depicted in Mahabharatha in chapters 52 to 79 in Vanaparvam as told by Sage Brihadaswan to Dharmaputhra to exemplify the unfortunate turn of events that might take place in the lives of great men and how such things bring them greater glory and prosperity. In the 18th century, Unnayi Warrier structured the contents of this story as Nalacharitham Attakatha to suit the art-form Kathakali, making it more dramatic and full of action. This version he made is so long that it had to be divided into four parts — First, Second, Third and Fourth Day — because each part needed a full night to enact the story. Nalacharitham is a considered the most romantic work of art constructed on the classical basement of Kathakali.