On Route 110, Sapphire is contemplating about Steven's whereabouts. She resolves herself to challenge the Gyms and progress across Hoenn to search for clues. While overlooking Mauville City, Sapphire notices that the patch of grass she is standing on is markedly different to the other sections, and she springs a pitfall trap. While dangling, Sapphire wonders where she has gotten to but is unable to see due to the perpetual darkness.
Sapphire manages to free herself from the trap by swinging out of it, landing hard on her rear. As she does so, she is approached by a mysterious looking robot, which proceeds to attack her with an array of punches. More robots then emerge, surrounding Sapphire. A huge robot disguised as a tree uproots from the ground, snatching Sapphire, Chic, and Rono. Sapphire shouts at the machine to let her go, but it then flings both Sapphire and her Pokémon onto a conveyor belt, leading to a railroad and eventually trapping them inside a ball.
Wattson and the Trick Master then emerge, celebrating their success in capturing a Donphan through a high five. Wattson then realizes suddenly that they mistakenly captured a human girl. The Donphan then appears, and on a rampage one of Wattson's robots, as Sapphire chides the two for mistaking her for a Pokémon. Wattson and the Trick Master then inform Sapphire that they were merely trying to capture the troublesome Donphan. They introduce themselves to Sapphire, who informs the two of her predicament with the pitfall trap. She asks whether that was one of their traps to capture Donphan, but they confirm that they only set the robot tree trap for Sapphire. Both Wattson and the Trick Master confer on the issue, asking one another whether they are thinking the same thing. Wattson concludes that Sapphire accidentally uncovered the entrance to the "Phantom Underground", New Mauville. Both Wattson and the Trick Master are ecstatic at this development, leading to Wattson creating a terrible pun, much to Sapphire's dismay.
The joke Wattson tells in the original version is lost in translation. In the Japanese version, he calls New Mauville "地下都市", or "Underground City" and makes a pun on the kanji used in it being near-homonyms for "近" and "遠し", which mean "near" and "far" respectively.