The two brothers of Champavati
In the kingdom of Champavati ruled two brothers of the same royal line. The elder, Mahidhwaja, was dharmic, gentle, and beloved of his people — every court day the daan-shala outside his palace was thronged with sadhus and the poor. The younger, Vajradhwaja, was fierce, jealous, and secretly nurtured a grudge against his brother's popularity, which he could not himself equal.
The murder in the forest
One day the brothers rode together into the forest to hunt. Deep in the woods, at a place where the peepal roots twist over a still pool, Vajradhwaja drew his sword and struck Mahidhwaja down without warning. He hid the body under the peepal's roots and returned to the palace claiming his brother had fallen to a tiger. The king's soul, denied its final rites, could not attain gati; it clung to the peepal and slowly hardened into a fierce brahma-rakshasa — hungry, raging, unable to leave that tree.
The traveller and Rishi Dhaumya
Years later, a traveller resting beneath that peepal at nightfall was seized by the brahma-rakshasa. Just as the man seemed lost, Rishi Dhaumya of the Kuru line passed by upon the forest road, and with the strength of his tapas held the pret still. Speaking in the language of the departed, he drew the whole terrible story from Mahidhwaja's mouth — the murder, the buried body, the stolen gati.
The vrat of Apara
Rishi Dhaumya said: 'Rajan, your gati was stolen by another's papa, not by your own. There is one vrat that can restore even that — the Apara Ekadashi of Jyeshtha Krishna Paksha. I will keep it for you, and give you every particle of its punya.' On the appointed day Dhaumya bathed at brahma-muhurat in a holy kund nearby, fasted the entire day in the strength of his tapas, and kept jagran through the night reciting Vishnu Sahasranama and the thousand names of Vaikuntha.
The release
On Dwadashi morning, as Dhaumya performed tarpan with Ganga jal and til at the peepal's root for the murdered king, a divine vimana descended from Vaikuntha with a blaze that lit the whole forest. The brahma-rakshasa dissolved like mist; King Mahidhwaja stood again in divya rupa, folded his hands in pranam to the rishi, and ascended to Vishnu-loka. Rishi Dhaumya's single vrat had done what a hundred shraddhas by the murdering brother could never do.
"Grants punya equal to a hundred yajnas, and is called the supreme pitru-tarpan Ekadashi for departed relatives who have not attained gati. Prescribed especially for those grieving an untimely or violent death in the family."