|"He must have seen us at the station and followed us onto the train!"|
|— Sokka to Aang after noticing Combustion Man.|
Aang and Sokka agree to accompany young Sho on a train ride to her grandmother's house. They are in for more than they bargained for, however, when the deadly assassin known as Combustion Man arrives.
Deep in the heart of the Fire Nation, Aang and Sokka behold a Fire Nation train while discussing the unfortunate absence of their friends Katara, Toph, and Appa, all of whom had their own reasons for staying behind. During this conversation, Aang spots a young girl standing alone in the crowd just as a man signals that it is time for boarding. After introducing himself and learning the girl's name, Sho explains that because her mother is sick, she must visit her grandmother's house alone. Aang proposes that he and Sokka ride the train with her, a plan that Sho and Sokka welcome with open arms.
On the train, while Sokka satiates his curiosity by sticking his nose into everything that does not concern himself, Aang comforts Sho. She is apparently still anxious about riding on the train, but he manages to teach her a method of how to relieve her worries. After taking deep breaths and thinking of her favorite animal like Aang advised, she feels a little better. This peace is short-lived as she notices a person on the train with a "weird symbol" on his head and becomes frightened once more. She reassures Aang that she speaks not of him but of the man who has just entered through a door in the back of the cart: Combustion Man.
The assassin wastes no time in pushing through, offhandedly shoving the ticket collector and marching, unfazed, through the cabin. Sokka and Aang unanimously decide that the two of them must get off the train before Combustion Man - who is obviously there looking for them - hurts someone else. Jumping out from his seat, Aang announces his presence, thereby distracting Combustion Man, and implores the assassin not to hurt the others. The firebender promptly makes the windows explode in the cabin, forcing Aang to grab Sho and jump away.
The train's conductor attempts to contact the engineer in order to stop the train on Sokka's advice, but the engineer does not respond, causing Sokka to head for the engine room while Aang handles Combustion Man. Before he leaves, Aang tells Sho to stay hidden and remember the breathing exercises he showed her while he is gone. Just as the Avatar leaves his hiding place, Combustion Man reveals himself and lunges at Aang. He escapes by jumping on his assailant's head and gliding on the air out of a hole in the train, causing Sho to gasp in surprise and begin to cry. Realizing that she has become distressed at the sight, Aang hovers by the window near Sho on an air scooter and tells her to take deep breaths, before goading Combustion Man into following him onto the roof of the train.
Meanwhile, Sokka bangs on the locked door of the engine room, ultimately using a piece of metal railing as a crowbar to pry the door open. The first thing he notices is that the engineer is unconscious, likely having hit his head during an explosion, leaving Sokka to stop the train on his own.
While Aang and Combustion Man brawl on top of the train, Sho meditates with her komodo rhino doll. Hearing the cries of her fellow passengers, she advises them to employ the deep-breathing exercises she is using now, calming many of them down. Back in the engine room, Sokka mutters to himself about the deficiencies of a hidden emergency break. He manages to find it and pull it just as Aang is about to fall into a body of water below. Seizing the opportunity, the Avatar turns around and bends a wave at Combustion Man, leaving the assassin in the water.
When Aang reenters the train to check on Sho, she shows him how well his breathing exercises worked on her as well as the other passengers. She is still worried, however, by the fact that, with the train so damaged, she will not make it to her grandma's house for dinner. Aang has a solution to the problem, though, revealing his bison whistle. He and Team Avatar end up flying away on Appa, with Sho constantly reminding herself to take deep breaths.
- Main article: Transcript:Combustion Man on a Train
- Since Aang and Sokka are still traveling in disguise and the name "Combustion Man" is used, the events of this comic book unfold between "The Runaway", wherein Sokka created the nickname, and "Nightmares and Daydreams", after which the gang no longer travels in disguise until much later.
- Aang believes that the reason Toph did not want to join him and Sokka on the train ride is because she had had enough experiences with trains in Ba Sing Se, alluding to the monorail Team Avatar rode in "City of Walls and Secrets".
- Toph is missing her bracelet in the final panel of the comic despite the story taking place after "Sokka's Master".
- When considered chronologically by the plot of the series, this is the second consecutive comic that makes this error, the previous being "Monster Slayer".
- Sokka wishes that Toph was in the train with him when trying to force his way through the metal engine room door, referencing her metalbending abilities.
- The train in the comic seems to be based on actual locomotives from the late 19th and early 20th centuries.