This story is based on a well-known episode from the epic Bhagavatha.
This "attakatha" was written by Aswathithirunal Maharaja around 1779.
King Kamsa, after hearing that a child has been born to kill him, decides to kill
all infants. He orders Demoness Poothana to slay Infant Krishna at Ambadi.
The scene starts with Demoness Poothana, disguised as a beautiful woman –
known as Lalita in Kathakali -- entering Ambadi and describing the beautiful
sights and smells of the place.
Then she enters Krishna’s abode and is
fascinated by the divine child. She starts playing with him. She can't bring
herself to kill such a beautiful baby. But she remembers the cruel Kamsa's
orders and shudders at her fate if she refuses to carry out the king's orders.
She is in a dilemma -- the mother in her won't let her kill a child but her survival
instinct tells her she has no choice. Reluctantly she decides she has to kill
Krishna.
Poothana smears poison on her breasts and starts suckling the baby. But after
a while she finds that the baby doesn't stop feeding; she feels cramped,
breathless; feels life oozing out of her little by little. The baby sucking at her
breasts is sucking out her life!
In the agony of her death throes, the beautiful Poothana is transformed into
her devilish form. Lord Krishna appears to her in his cosmic form or
"vishwaroopa" and Poothana attains salvation.