On the Lam is an episode in the Hey Arnold! TV Series.


Stinky, Harold and Sid are on the run after they think they blew up the police station.


Mr. Simmons shows his class a rocket-launching experiment with baking soda and vinegar. Harold wants to launch the rockets, but the bell rings before Mr. Simmons can supervise the proportions as Mr. Simmons tells everybody that they'll pick up where they left off tomorrow. Harold, Sid and Stinky then sneak into the classroom and steal all the rockets, baking soda, and vinegar from the science closet with Stinky also bringing his Louisiana hot sauce. Using Stinky's hot sauce with the other ingredients, they launch the bunch of rockets into an old police station building just as Ernie dynamites and blows up the building--however, not noticing Ernie and his construction workers, the boys believe that they blew up the police station and panic.

They run into Arnold's basement and try to hide there, but Stinky accidentally reveals what they did to Arnold, and they devise a plan:

  • Plan A is to get to the trainyard and hop a boxcar to go down south and live with Stinky's grandmother.
  • In case they can't find Stinky's grandmother, Plan B is to disguise themselves and become hobos.

Arnold believes there has to be a logical explanation to the trio's story and suggests they should go to the police and find out what actually happened. So Harold ties Arnold up and gags him to stop him from ratting them out. When Stinky, Harold and Sid's parents discover that the boys are missing, they get really worried (especially Harold's mom).

On the way to the trainyard, Harold, Stinky and Sid encounter multiple cops in the process while Phil leaves Arnold to his game of secret agent. Eventually, Arnold frees himself by hopping up the stairs and explaining to Grandpa Phil and Ernie about what happened to Harold, Stinky and Sid and their plan to become hobos. Ernie tells Arnold that Harlold, Stinky and Sid didn't blow up the police station, he did with his construction crew (he also states it had been slated for demolition for months). Arnold convinces Grandpa and Ernie to go with him to the trainyard to stop the boys and clear up the misunderstanding. 

Harold, Stinky, and Sid make it to the trainyard and encounter real hobos after ditching their costumes. Their parents, Arnold, Phil, Ernie, and the police manage catch up with them scaring them out of the train car. They manage to get onto the roof of a train car, but several spot lights shine on them. They decide to give up as they are cowards and confessed to everybody that they blew up the police station. Harold, Stinky, and Sid sob, saying that they didn't mean to blow up the police station and that they didn't mean to hurt anyone and it was a harmless prank, but Arnold tells them that they didn't actually blew up the police station.

Ernie corrects them by revealing the truth: he and his workers demolished the station, not the boys. Harold's mom is relieved to have him back and hugs him tightly. With the entire misunderstanding cleared up, everyone has a good laugh. Harold apologizes to Arnold for tying him up. But then Mr. Simmons comes in, having seen the whole thing on TV. He then tells the boys that they will be punished for stealing from the science closet, much to Harold, Stinky and Sid's dismay.