Plot summary
A dying monk delivers a letter from Lao Ma that sends Xena back to Chin in search of her book of wisdom. At the monastery, Xena and Gabrielle encounter soldiers using black-powder explosives and receive help from Pao Ssu, who introduces herself as Lao Ma's daughter.
The book is missing. While Gabrielle and Joxer investigate the formula for the explosives, Xena follows the book's trail with Pao Ssu. They find it with Pao Ssu's twin sister, K'ao Hsin. Pao Ssu's determination to seize its power reveals that she is connected to the attacking army. Xena tricks her into taking a false copy.
Gabrielle and Joxer are arrested while asking about the explosive ingredients, but escape using a small amount of powder. Pao Ssu captures them again and ties them to carts rigged to explode. K'ao Hsin surrenders the genuine book to save them, yet Pao Ssu lights the fuses anyway. Xena stops one explosion and pulls Joxer clear of the other.
The friends identify the powder's missing ingredient and use explosives to disrupt the warlord Go Kun's forces. Xena and K'ao Hsin study Lao Ma's teachings and discover how to access their extraordinary powers through pure joy. Pao Ssu has reached the same power through undivided hatred.
During the final confrontation, Xena and K'ao Hsin undermine that hatred by explaining that Lao Ma surrendered her daughters to protect them, not because she did not love them. Pao Ssu loses her advantage and is defeated.
Kun's soldiers then accidentally ignite their own supply of powder while trying to help her. With their leader gone and the weapons destroyed, the attack collapses and the immediate danger ends.
Credits
Adapted from Legendary Journeys Wiki contributors, Purity. Complete episode narrative, rewritten and condensed for clarity; causal developments and the episode's ending retained. Illustrations, dialogue quotations and non-story metadata omitted.