The Sundara Kanda is the fifth chapter of Ramayana forms the plot of the famous Hindu epic and mainly deals with Hanuman's heroic journey to Lanka.
Sage Valmiki named it after the name of Hanuman. Hanuman was fondly called Sundara by his mother Anjani. Valmiki chose his name as this is the only chapter in Ramayana which revolves around the adventures of Hanuman rather than the heroism of Rama Chandra. Valmiki was the first person who scripturally records the tale of Ramayana in Sanskrit. Hanuman's selflessness, strength, and devotion to Rama have been depicted all over the chapter.
Hanuman takes a leap across the ocean to reach Lanka. Once in Ravan's kingdom, Hanuman looks for Sita everywhere. He meets Vibhishan, who tells him that Sita is being kept in Ashok Vatika.
In Vatika, Hanuman witnesses Ravan wooing and threatening Sita.
Once the demon king leaves, Hanuman comes before her and tries to convince her to come back with her. He presents Ram’s ring as proof of his alliance. But she refuses to come with him, as she wants Ram to come and avenge the insult of his wife's abduction.