When "Day of the Black Sun" Part 1 ended, Aang, Katara, Sokka and the combined forces of the Water Tribe's fleet and the Earth Kingdom's forces were making their way to the capital, while Prince Zuko finally realized that he was on the wrong side, and the only one who can restore his honor is himself, not his father.
When Sokka, Toph and Katara break away from the forces in order to help Aang find Ozai, they end up in a massive maze of underground tunnels created by the volcano they are in. Eventually they find Ozai's chamber, only to discover Zuko's sister, Azula, waiting for them. Amazingly enough, she knew their plan and the effect the eclipse would have on firebending, and devised a plan to keep our heroes from Ozai. What ensues is a great battle using all of their various bending abilities, but by the time the group realizes Azula is just trying to waste their time as the eclipse passes, it is too late.
Meanwhile, Zuko approaches his father and tells him of his decision to leave the Fire Nation and join Aang's party. While Aang won't be able to defeat Ozai during the eclipse, with Zuko teaching him how to master firebending, he will one day be able to appear and stop the Fire Lord.
Because of the time wasted, even though the invasion force was able to secure a hold on the Fire Nation capital, Ozai's continued existence means that they were all captured. But before their imprisionment, the invasion fleet decided to give the kids a chance to escape. Riding on Appa, Aang and the gang leave the capital and head for the Western Air Temple.
After arriving in the hidden temple, the gang realizes that the only way to stop the Fire Nation is to rely on their old plan; get Aang to master all four elements and defeat Ozai before Sozin's Comet arrives and tilts the balance of power into the firebender's favor for good. Hope seems lost for finding a firebending master on such short notice, that is, until the gang realizes they've been followed by Zuko. As you would expect, there are a lot of tense moments where Zuko tries to explain his defection, and the others reject him. But eventually, the former prince proves himself; unfortunately, with his change in sides and loss of rage, Zuko's fire bending is less than impressive.
In "The Firebending Masters," Zuko and Aang travel to the land of the Sun Warriors, the original firebenders, in order to find the original source of firebending, a source that doesn't require hatred and rage. Imagine their surprise when they find the ancient city is still populated. The two will have to prove themselves worthy to learn from the original firebending masters if they are going to gain control over the most chaotic element.
The last half of Volume 3 has Sokka and Zuko planning to sneak into the Fire Nation's top-security prison in order to save Sokka's father. According to Zuko, a prison called "The Boiling Rock" is where all of the most dangerous criminals are sent, but when they arrive on the island (which is surrounded by a boiling lake), they don't find any war prisoners. But Sokka does find a lost love, Suki (whom viewers might remember as the leader of the Kuoshi Warriors).
As the second-to-last volume of the series' final season, a lot happens on this DVD. Sokka's invasion plan fails, but inspires them to fight on, plus it leads to Aang finally getting a firebending master to teach him the final element and hints of the final battle with the Fire Nation.
