In the epic, she is described to have convinced Queen Kaikeyi that the throne of Ayodhya belonged to her son Bharata and that her step-son—crown-prince Rama (the protagonist of the Ramayana)—should be exiled from the kingdom.

[1] Manthara reminds Kaikeyi of the two boons Dasharatha had given her when she had once saved his life in a celestial battle.

Manthara reckons that the fourteen-year banishment would be long enough for Bharata to consolidate his position in the Empire and weave his way into people's hearts.

Having been rewarded by Kaikeyi with costly clothing and jewels, she is walking in the palace gardens when Bharata and his half-brother Shatrughna come upon her.

Kaikeyi begs Bharata to save her, telling Shatrughna that it is a sin to kill a woman and that Rama would be furious with them both if he does such a thing.