After Stu sells an invention, he tells the kids that he's planning to buy them a swimming pool in the backyard. While digging up the yard, the construction crew unearths the Rugrats' old mechanical Reptar toy. The kids fondly remember it (all of them but Dil), but decide to throw it away, until, during an electrical storm, they become convinced that they have angered Reptar. They ultimately decide to rescue the toy, and realize that, although they are growing up, they cannot forget their past.
The movie they watch and the whole episode is possibly a parody to the 1982 film, Poltergeist. The family digs up something, throws it away, and a curse happens. Reptar is the curse that they threw away (not really, just faulty pipes).
A flashback of Tommy, Chuckie, Phil, and Lil as Rugrats along with Spike playing with Reptar is shown. This marks the first episode to feature Tommy as a Rugrat in All Grown Up, the third time for Chuckie, and the 2nd time for Phil and Lil.
Ending Tagline: "Come on, guys! I smell herring!" - Dil