-->"You shouldn't give 100% of your energy into any one strike. You've gotta be quick and accurate. Hit a series of points, and break your opponent's stance. And when he's reeling back, you deliver the final blow. His own weight becomes his downfall. Literally."

Aang and his friends have finally reached Ba Sing Se, only to discover that the city is under attack from the Fire Nation, led by Azula, Mai, and Ty Lee, who are using a giant drill. Initially, the commanding general in charge of fending off the attack is reluctant to accept the team's help, but after Mai and Ty Lee quickly dispatch the general's "Terra Team", he changes his mind. Seeing that outer attacks have no effect on the drill, and using Ty Lee's chi-blocking as inspiration, Team Avatar goes inside the drill to take out its weak points and hopefully bring it down before it breaches the city's outer wall.

Meanwhile, Zuko, Iroh, and the Freedom Fighters reach Ba Sing Se as well. Jet is set on getting Zuko (or as Jet knows him, "Li") to join the freedom fighters. However, when Jet sees Iroh warm up a cold cup of tea, he realizes Zuko and Iroh are firebenders...

!!Tropes
* AttackItsWeakPoint: Drives a good half of the plot.
* BeautyIsNeverTarnished: Averted: By the end of the climactic battle, everyone ([[CrowningMomentOfFunny excluding Mai]]) is covered in slurry.
* BrainBleach: After Zuko sees Uncle Iroh bribe a large woman to get the ferry tickets: "I'm gonna forget I saw that." Complete with FacePalm.
* BigNo: Iroh gives one when Zuko knocks the freshly heated tea out of his hand. PlayedForLaughs.
* CloudCuckooLander: Ty Lee, naturally. "Look at that cloud. It's so...poofy. Poof!"
* CurbStompBattle: Ty Lee and Mai, two teenaged girls against General Sung's top team of earthbenders.
* DangerouslyGenreSavvy: Azula, of course. She is immediately on her guard when the general has his NothingCanStopUsNow moment.
* DistractedByTheSexy: Sokka leaves himself wide open to attack when Ty Lee flirts at him. Katara pulls him out before anything bad happens, though.
* DramaticDeadpan: Mai: "[[EmotionlessGirl We lost.]]"
* DrillTank: Obviously.
* GetAHoldOfYourselfMan: Sokka to General Sung, spoken word for word.
* GettingCrapPastTheRadar: This may have intentional innuendo on the writers' part; but a long, narrow drill, penetrating through a hole that explodes with a goopey mess when it blows up on the inside? Said mess is coated all over everyone by the end, Sokka's trying to brush it off his tongue, the war minister looks at it with disgust as it smears down the watchtower window, it flies up so high it hits Sung from atop the wall, and of course, as it spews out the back of the drill in overflow, Toph says this line:
-->'''Toph:''' [[FreudWasRight HERE IT COMES!!]]
** Now what does all ''that'' remind you of?? And now you know the ''real'' reason Mai refused to follow Ty Lee down into the slurry.
* GilliganCut: Aang and Azula are fighting on top of the drill, when boulders start raining down on them.
-->'''Aang:''' (''shouting to the general on top of the wall'') General Sung! Tell your men to stop throwing boulders down here!
-->(''cuts to the top of the wall'')
-->'''General Sung:''' Whatever you do, men, don't stop throwing boulders down there!
* NothingCanStopUsNow: Qin to Azula because he's so confident in the drill.
* OminousWalk: Azula pummels Aang into near-unconsciousness and then ominously marches towards him while she readies a fire attack to presumably finish him off.
* OneManArmy: Ty Lee takes down a good twenty earthbenders by herself.
* ProperlyParanoid: For once, Jet is right on the ball when assuming Iroh heated his tea with firebending.
* PungeonMaster: While throwing around names for the team, Sokka comes up with this:
-->'''Sokka:''' How about...the Boomerang Squad! [[DontExplainTheJoke See, it works because it's got the word "Aang" in it! Boomer-AANG]]."
-->'''Aang:''' [[PetTheDog I kinda like that one.]]
** He then goes on to think of Team Avatar and the Aang Gang (close enough to the [[FanNickname Gaang]]). ItWillNeverCatchOn.
* ShoutOut: When Sokka is throwing around names for the team, he suggests "Fearsome Foursome", the name of the legendary defensive lines of the NFL's Los Angeles Rams in the 60's and 70's.
* ThemeMusicPowerUp: A rare example for ''[[WesternAnimation/AvatarTheLastAirbender Avatar]]'': When Aang starts running down Ba Sing Se's outer wall to deliver the final blow, the main theme kicks in to accompany him.
* ThisIsADrill: There's a reason this episode is named "The Drill".
* VictoryPose: A minor example: After Aang is successful he gives a massive goofy grin, which is all you can see of him under the mud.
* VisualInnuendo: The Drill itself, of course.
** FreudWasRight: Not to mention the fact the drill is penetrating Ba Sing Se, filled with a slurry of rocks inside that explodes out of the drill, and splatters all over the place when it gets taken out of commission. Sure, as a kid, this doesn't dawn on you, but as an adult... it's the ultimate case of GettingCrapPastTheRadar.