Zuko prepares to teach Aang firebending, but for unknown reasons cannot firebend. He and Aang travel to the temples of the extinct Sun Warriors to learn about the ancient origin of firebending. Zuko reveals to Aang that his great grandfather caused the extinction of the dragons, the original firebenders. After discovering the Sun Warrior culture still exists, Zuko and Aang are sent to see the firebending masters, later revealed to be the two last surviving dragons in the world. After teaching them the true nature of fire, Zuko's powers are restored and Aang no longer fears firebending.
Zuko commences Aang's firebendingtraining at the Western Air Temple, and tells Aang to show him how much fire he can produce. Seeing as it is not very much, Aang thinks perhaps a demonstration from Zuko would help. However, Zuko finds that his own firebending is very weak; he tries to firebend at lower altitudes, hoping that it is the height hindering him, but to no avail.
Later that night, Zuko apologizes to everyone, saying he has lost his firebending. Out of spite, Katara laughs and coldly jokes how convenient it would have been for the group if Zuko's firebending had failed him months ago. Aang hypothesizes that Zuko must not have enough rage to create fire like he used to in the past. Sokka, saying then all they have to do is make Zuko angry, starts poking him wildly with his sword sheath. However, Zuko says that he no longer wants to rely on anger and hatred, so Toph encourages him to learn from the original source of firebending, like how she learned earthbending from the badgermoles, who were the original earthbenders. Zuko says that the dragons were the original firebenders, but that they have been extinct for some time. Aang comments that when he was a kid there were many dragons and AvatarRoku had a dragon, but Zuko does not find it very helpful. Searching for an alternate but equally viable source, Zuko then tells Aang about an ancient civilization that died out thousands of years ago called the Sun Warriors. It turns out that the current firebending country—the Fire Nation—inherited their skills from this ancient race and twisted them into a more aggressive style.
Zuko and Aang fly to the Sun Warrior ruins on Appa, they land and start exploring the ruins. Aang nearly falls into a trap, which Zuko is surprised to see still works even after centuries of being built. He then bypasses the trap by running across the adjoining wall. Aang is hesitant to continue, but Zuko edges him on and they find a massive stone carving depicting dragons and a Sun Warrior.
In the mural, two of the dragons are breathing fire onto the Sun Warrior. Aang is surprised because he got the impression that the dragons were friends with the Sun Warriors, while Zuko remarks that they had a funny way of showing it. Aang asks Zuko what happened to the dragons, and Zuko reveals that the dragons became extinct because Fire LordSozin started the tradition of hunting them for glory and the title of 'Dragon'. He tells Aang that the person who killed the last living dragon was his uncle, Iroh.
While exploring the ruins, Aang and Zuko come across a locked door with a sunstone on top. Zuko sees a celestial calendar is used to open the door specifically on the summer solstice, and uses his sword to reflect sunlight onto the jewel, causing it to open. Aang compliments his intelligence, telling him he "doesn't care what anyone else thinks". Inside they find various statues which depict a firebending form called the Dancing Dragon.
Aang imitates the first statue and discovers there are tile switches linked to the dance positions. He persuades Zuko to perform the dance with him and as they do, they activate an ancient key mechanism. Upon completion of the Dancing Dragon, a pedestal with a huge gold, egg-shaped gem rises in the middle of the room. Zuko picks it up despite Aang's warnings, inadvertently triggering a trap. The chamber doors close, and a glue like substance fills the room. Zuko and Aang find themselves trapped by the liquid in a barred skylight where they have plenty of air but no way to get free. They are then captured by the still-flourishing Sun Warrior tribe, which accuses them of attempting to steal Sun Warrior treasures.
After explaining that Aang is the Avatar and they desire to learn the true form of firebending, Zuko and Aang are put through a ritual where they have to carry a portion of the first fire, given to man by the dragons, up a mountain and present it to the true "firebending masters", Ran and Shaw. At first, Aang is scared to try to hold the flame, but the Sun Warrior chief comforts him by saying that fire is not just destructive, but it is life.
They reach the lair of the masters and are sent to the top of a stairway, where they see two caves at the top. Aang and Zuko present their fires and each face one of the two caves. Aang, however, loses his portion of the fire due to being distracted and scared; he then tries to get a piece of Zuko's fire, but accidentally knocks his hands down, extinguishing his flame as well. At that moment, two dragons emerge from the two caves, to Zuko and Aang's great shock, and start flying in circles around them. Zuko and Aang earn the respect of the dragons by performing the firebending technique that they learned from the statues, dancing with the dragons in the process. The dragons then breathe beautiful, multicolored flames around them, revealing the true and harmonious way of firebending.
When the dragons return to their caves, Zuko understands the reason he could not firebend was because he had lost his "inner fire". He used to draw his fire from rage, anger, and his burning desire to capture Aang, but after he joined the group, he could no longer draw from this source. However, after watching the dragons, he learns that he can draw from the true source, his desire to help bring balance to the world. He describes this new found feeling as "the sun [but] inside of you".
Aang realizes that fire is not destruction, but energy and life, and is able to firebend as well. The chief explains that Iroh was the last outsider to visit the masters and deemed worthy to learn the secret. He lied to keep the dragons alive so they could continue on. The chief explains he has no choice, but to imprison the both of them forever to keep their existence a secret, which astonishes them both. He soon reveals that he is joking, but is very serious that they do not tell anyone.
Back at the Western Air Temple, Zuko and Aang show everyone the firebending moves they learned. Sokka pokes fun at them by saying that "they will just tap-dance [their] way to victory over the Fire Lord." Zuko tries to explain how serious and ancient the technique is, but they cannot look past the name of the form, the "Dancing Dragon", so they do not take it too seriously.
This episode shows Toph learning earthbending from badgermoles. She had previously stated she learned it from them in "Sokka's Master".
Katara continues to be cold at Zuko after he is finally accepted to the group from the previous episode. She remarks at the irony of him losing his firebending.
The song chanted by the Sun Warriors to call forth the Masters is the same as the Avatar series ending credits song.
The close-up of Aang shown as his first burst of fire is disappearing mirrors the close-up from "The Deserter" when he makes a ring of fire that results in Katara getting burned. That episode taught him the dark side of firebending and caused him to steer away from ever using it again; this one teaches him the true art, thus breaking that mental block.
When Sokka approaches Zuko and Aang training to ask if he can watch "you two jerks do your Jerkbending", his right hand holding his apple goes from being bare, to gloved, to bare again. His left hand is also seen going from gloved to bare.
When Sokka attempts to make Zuko angry by poking him, Appa is seen eating in the background, but when Zuko says he does not want to rely on hate and anger anymore, Appa is missing.
When Zuko tries to 'speed up time' when they outsmart the sun stone he takes out one of his dual swords. But a few frames later he has both out.
When the Sun Warriors show Aang and Zuko the first fire that was given to man by the dragons, they are seen sitting in three rows, but in a later frame there is only one row.
When the Sun Warrior instructs Aang and Zuko with, "Those who wish to meet the masters Ran and Shaw will now present their fire", Aang and Zuko are already in a bowing position, offering their fire. When it cuts back to a close-up of them, they are merely standing and staring at the procession of Sun Warriors below them before going into the bowing position.
The music the Sun Warriors play, as Zuko and Aang walk up the stairs, is noticeably off beat. The motions made by the drummers do not match the "chuu-chaa-chuu-chaa-chuu-chaa" noise.
When Zuko and Aang are being surrounded by the dragons' fire, for a split second, Zuko's scar can be seen on his right eye instead of his left and his swords are on his right shoulder. Also, the flame is moving clockwise.
When the glue began sprouting out, the egg next to Zuko was hanging because of the glue, but when Aang tried to airbend at Zuko to free him from the glue, it was gone.
Iroh has the title "Dragon of the West". This was previously explained to be because of his fire breathing ability. However, this episode explains that Iroh earned this title through apparently slaying the last dragon. It seems that Iroh considers himself a dragon because of his fire breathing technique, possibly as a sense of personal justification, but the Fire Nation considers him a Dragon because of his apparent slaying of the last dragon, although this seems to be more of a cover-up on Iroh's part as the Sun Warriors depend on the secrecy of their existence to survive.
Iroh stated in the episode "Bitter Work" that, "lightning is not fueled by anger and rage like other firebending is" even though he knows the true fuel of firebending. Although, this could be that he is trying to protect the secret of firebending from Zuko.
Many fans believe that the golden artifact is really a dragon egg, mainly because Zuko said that the artifact felt alive.
When Zuko is about to pick the golden artifact up, Aang states he is "very suspicious of giant glowing gems sitting on pedestals". This is most likely a reference to the booby-trapped Golden Idol from the popular movie Raiders of the Lost Ark.
The fire scene is similar to the eternal flame at John F. Kennedy's grave at Arlington National Cemetery in Washington D.C., but may also refer to the eternal flames in Jewish temples.
Ran and Shaw resemble the dragons from Zuko's dream in Ba Sing Se, a red dragon and blue one.
The Sun Warrior's culture resembles that of the Aztecs.
The Sun Warrior's architecture resembles that of Indian Buddhist Stupas and Tibetan monasteries.
The bow that the Sun Warriors did after Ran and Shaw judged Aang and Zuko was identical to the bow that the students did in class to their teacher in "The Headband".
To get across the first booby trap, Zuko performs a Wall Run, widely used in Parkour and free running to overcome large gaps or high platforms. Other Parkour moves are accomplished in the series also, mostly performed by Suki and Azula.
This episode kicks off "Countdown To The Comet".
This is first time when more than one master is presented to someone who wants to master an element.
The scene where Zuko uses a wall run to cross the spike pit in the ancient ruins is similar to the "Prince of Persia" video game, in which the prince, armed with a sword like Zuko's would run across walls to avoid pits and traps, possibly having been the inspiration for the scene.
The final move of the Dancing Dragon is reminiscent of the "Fusion" move in Dragon Ball Z.
The music the Sun Warriors play while Aang and Zuko climb the stairs is the end credit music for the show.
When the names Ran and Shaw are combined, they formulate the first part to the traditional Chinese phrase 燃燒中, which means "aflame".
From this episode on, Zuko does not grunt in anger every time he firebends, which was something he did frequently in seasons 1 and 2 and part of season 3.
While climbing the mountain, Zuko tells Aang he is a talented kid and that he can control his fire in order to ease his anxiety and give him confidence. This is another example of how well Aang responds to positive reinforcement.