Danville's resident child prodigies, Phineas Flynn and Ferb Fletcher were sitting underneath the tree in their backyard as usual, with their pet platypus, Perry lying down in the grass in front of them.
"So, Ferb. What do you wanna do today?" Phineas asked his British stepbrother, after which Ferb proceeded to put his right index finger to his lips in an inquisitive manner as he tried to think of what he wanted to do today. His mouth then fell open as he pointed his index finger in the air, as if he got an idea and proceeded to show Phineas something in the magazine he was reading.
"The Danville Caverns? Why show me this?" Phineas asked Ferb, wondering where he was going with this.
"Well, according to this article, there's a special crystal inside the Danville Caverns, and that crystal could be of use to us in the building of our inventions." Ferb explained to Phineas.
"A special crystal? That we could use in the building of our inventions? That's genius! Ferb, I know what we're gonna do today! Let's gather all the equipment we can and go on an expedition through the Danville Caverns!" Phineas beamed as he got up with Ferb doing the same thing. The brothers then proceeded to go gather all the equipment they needed for their expedition.
The scene then cut to the inside of the house, where Phineas and Ferb's mother, Linda Flynn-Fletcher was working in the kitchen. Phineas and Ferb then proceeded to enter the house, with Phineas being dressed as Baloo from Tale Spin and Ferb being dressed as Indiana Jones.
"Hey, mom! Ferb and I are going on an expedition through Danville Caverns!" Phineas told his mother as him and Ferb began walking towards the front door.
"Sounds fun, sweetheart! Be careful!" Linda replied to her son as she continued to work in the kitchen. Phineas and Ferb then got outside, got onto their bicycles and began pedaling towards Danville Caverns. As they did, their older sister, Candace proceeded to peek her head from her bedroom window, squinting her eyes in suspicion.
"What are those two up to? Probably no good...I must follow them to see what they've got planned for the day." Candace declared as she quickly grabbed a backpack filled with camera equipment before jumping out of her bedroom window, getting on her own bicycle and following after Phineas and Ferb.
As Phineas and Ferb were pedaling through the city to get to Danville Caverns, a realization suddenly hit Phineas. "Hey, where's Perry?" He asked no one in particular.
Perry was still back in the Flynn-Fletcher Residence's backyard, lying in the grass. Scanning his eyeballs around the backyard to make sure that no one was around, he quickly got up on his feet, put on his signature fedora and stepped inside a secret entrance hidden inside the tree he was just lying in front of. Taking an elevator down to the O.W.C.A. Lair, he quickly entered the lair and sat down in the chair in front of the computer screen, as he was about to receive his daily mission briefing from Major Monogram.
"Good morning, Agent P. We have received intel that Dr. Doofenshmirtz is searching for a special crystal inside Danville Caverns. What he's planning to do with that crystal, the intel didn't mention, but you can reckon that he's got malicious intentions behind finding the crystal. You must stop Dr. Doofenshmirtz before he can get to the crystal and use it for his malicious scheme." Major Monogram informed Perry, who saluted to show he understood the assignment and proceeded to get off of his chair and walked over to the garage, got into his flying car, left the O.W.C.A. Lair and took off for Danville Caverns.
Meanwhile, Phineas and Ferb had made it over to Danville Caverns and parked their bicycles outside. "Well, here we are, Ferb! Danville Caverns! Let's go inside and find that crystal you were talking about!" Phineas told his brother, who nodded as the two of them proceeded to grab two conveniently places lit torches that were hanging on the wall and ran inside the caverns.
Shortly afterward, Candace arrived at Danville Caverns as well as she parked her bicycle outside as well before quickly grabbing a camera out of her backpack and turning it on. "You two are so busted when I get video evidence of what you've been up to in here..." Candace smirked to herself as she quickly ran into the caverns herself.
Not too long after this, Perry arrived at Danville Caverns himself, although unlike Phineas, Ferb and Candace, he took his flying car to the top of the caverns and went through a hatch that was placed on top of there. We were then shown a shot of Dr. Doofenshmirtz's underground lair.
"Doofenshmirtz Underground Lair!" Doofenshmirtz's evil jingle sounded before we were shown a shot of Dr. Doofenshmirtz working on his computer inside his evil lair as he tried to locate the special crystal he was looking for. He suddenly heard the sound of Perry's flying car landing and turned to look as he saw Perry walking into the room.
"Ah, Perry the Platypus! I was wondering when you were going to show up!" Dr. Doofenshmirtz greeted Perry before quickly grabbing a remote and pressing a button on it that caused a cage to drop down from the ceiling that trapped Perry inside.
"Now you're probably wondering why I'm searching for a special crystal inside Danville Caverns, aren't you?" Dr. Doofenshmirtz asked Perry, who didn't appear to look too interested in the backstory he was about to be told.
"Well, it all started at my high school's Valentine's Day dance, when I was a 14 year old high school freshman. There was a girl named Eloise who was as pretty as a bouquet of red roses, and I had a crush on her for the longest time. At our high school's Valentine's Day dance, I wanted to ask her to dance by giving her a bouquet of dandelions I had plucked myself earlier that day, but one of the popular kids, a boy named Karel beat me to it by asking Eloise to dance with a special crystal he had bought from a jewelry shop earlier that day. Eloise was overjoyed by being gifted this special crystal and proceeded to dance the night away with Karel, leaving me without a dance partner, my heart broken and my Valentine's Day dance ruined." Dr. Doofenshmirtz explained to Perry as flashbacks of the events he described came by before cutting back to the present day.
"In a magazine I got on my doormat this morning, I read something about a special crystal being hidden away inside the Daville Caverns, with the article talking about how this crystal holds unimaginable powers. So, when I find this crystal, I'm going to use it as an energy source for my newest invention; The Jewel-B-Gone-Inator!" Dr. Doofenshmirtz continued to explain to Perry as he unveiled a large laser cannon, which was the Jewel-B-Gone-Inator he was referring to.
"When this special crystal fuels my Jewel-B-Gone-Inator, it will fire a laser across the Tri-State Area that will cause all jewelry stores to disappear, and then no one can buy their special someone a jewel as a gift anymore!" Dr. Doofenshmirtz triumphantly and evily declared, with Perry rolling his eyes at how dramatic Doof was being.
"Hey, don't roll you eyes like that, Perry the Platypus!" Dr. Doofenshmirtz told Perry, being offended at Perry rolling his eyes at him, with Perry rolling his eyes once more in response. "No matter! I must continue searching for this special crystal, so be a good platypus and stay in your cage, alright?" Dr. Doofenshmirtz told Perry before turning back to his computer and began continuing his search for the special crystal.