During the exile, Lord Rama and Lakshmana met Hanuman. He then took them to Sugriva. They then struck a deal where Lord Rama would help Sugriva get back his kingdom and Sugriva would help Lord Rama in his search for Sita. Sugriva came from his exile and challenged Bali, when Lord Rama killed him. He was reinstated as the king of Kishkindha and he sent an army of monkeys along with Hanuman to help Lord Rama save Sita from Ravana. Lord Rama then sent the monkeys in all directions to search for Sita, but however they could not find anyone and in South India, they were stopped by the ocean. At this time, Sampathi, who was the brother of Jatayu, came to help them as he had heard about his brother’s death. Though he was old, he could still see very well and using his powers of sight, he was able to see that Sita was in Lanka, captured by Ravana.
Lord Rama then told Hanuman to meet with her and tell her that he would soon be coming to rescue her. He also gave his ring to him, so that he could give it to Sita as a proof of Rama’s word. Hanuman then grew so big in size that the mountains nearby were smaller than his feet and in a single leap, he reached Lanka. After reaching Lanka, he took the form of a normal monkey and waited until night to approach Sita. At night, he went to her and gave her Rama’s ring. Sita broke down into tears with happiness and she gave her ring to him, in order to show that she was still alive in Lanka. Hanuman took the ring, but immediately, he was seized by Indrajit (son of Ravana) and taken to the palace of Ravana. There, Hanuman told Ravana to return Sita in order to avoid any more conflict, but this only angered Ravana and so he ordered his guards to set fire to the tail of Hanuman.
Hanuman got an idea and as soon as his tail was set on fire, he grew in size, breaking his shackles and he flew around Lanka, setting fire to all the buildings and trees and destroying everything. After this he jumped into the ocean to douse the fire on his tail and then he returned to Lord Rama. He gave him the ring and Lord Rama was very happy to see that Sita was still alive and well.