Danny fights off a ghost squid, wolf, and cobra all in the course of one night. Distress over all the ghosts coming out at once, Danny wonders why there's so many to begin with. The answer is given when Jack tests his new genetic lock that opens the Fenton Ghost Portal only by the press of a button through a Fenton family member. Unfortunately Jack (while showing it off to Maddie and Jazz) keeps pushing it one too many times, releasing one ghost per button press. A ghost named Johnny 13 and his girlfriend Kitty races for the portal on his motorcycle. Telling his shadow to keep the portal open, Johnny races in before it closes. Unfortunately they barely just make it, the portal closing and zapping Kitty. Unable to maintain a solid form, she spreads her energy to her jacket, ring, and scarf, telling Johnny to find a host to wear it so she can conceal herself in that body. Kitty heads back to the Ghost Zone while Johnny vows to find a body, which he quickly does so when he eyes Jazz upon entering Earth.
The carnival is approaching and Tucker manages to ask a girl out, unfortunately his technology is off putting and she leaves, viewing him as a techno geek, upsetting him. Meanwhile, Danny encounters Johnny 13 and loses the battle as well as the ghosts he caught previously when Johnny's Shadow sends a lamp post that hits the Thermos as Danny rolls to safety.
At the carnival, Danny tells Sam and Tucker about his recent encounter with Johnny. Sam asks Tucker to use his PDA only to be picked on by Dash and Kwan. Tucker has finally had it with being labeled a "techno geek", so instead of helping, he tries to find another nickname to give himself. Meanwhile, Johnny sends his Shadow to move a truck (which Tucker stood next to) making it crash towards the roller coaster support railings. Danny rescues the inhabitants in the roller coaster, but the coaster itself heads straight for Jazz. Occupied with the rescuees, Danny unfortunately doesn't make it in time, but luckily Johnny saves her life. Immediately she expresses gratitude and develops a crush on him. Johnny then offers Jazz Kitty's scarf while Danny watches the two, unhappy with their sudden budding relationship. Tucker in the meantime faces the problem of now being labeled "Bad Luck Tuck" by his peers.
Danny and Jazz's roles are reversed when he ends up being the overprotective sibling over another due to their rambunctious decisions, and so is absolutely livid when he sees Johnny's bike parked near his home and even more so when he nearly kisses Jazz (after offering her Kitty's jacket). Wanting to be alone together, Jazz takes Johnny to the basement where she shows off the Fenton Ghost Portal. Jack and Maddie comes in time after Danny rats her out, stating unauthorized people are not allowed in the basement, prompting Johnny to leave.
By school the next day, Danny concerns over being in the same thought bubble as his parents while Tucker tries to convince others he is not bad luck, only for Johnny's Shadow to cause even more for him by making him accidentally toss his spoon to a bee's hive, stinging nearly everyone in school. After school, Danny sees Jazz drive off with Johnny and gives chase. Johnny spots Danny and sends his Shadow to attack, the dark creature ultimately trying to suffocate him. Johnny in the meantime offers Jazz Kitty's ring, asking her to be "his girl". Danny manages to break free from the Shadow through his ecto ray, figuring out bright light weakens it. He heads to the local movie theater where Sam suggests to Tucker to get a new image to reduce his "bad luck" status at school. Danny in the meantime manages to send the Shadow away through the light of a movie projector.
Johnny again asks Jazz about the ring, which she is thrilled to have. Just as he almost slips it on her, Danny flies by, turns human, and lands right in front of the two. Upset that she was spied on, Jazz rats him out to Jack and Maddie who pretend to punish Danny, but secretly praise him for spying, not trusting Johnny as well. The next day, Tucker is now a goth thanks to Sam, but refuses to wear the make up associated with it while Danny continues his concern that he is being like his parents, and that his sister is dating a ghost.
Later that night, Jazz sneaks Johnny into her house and to the basement where he once again tries to give her the ring. Danny interrupts and shakes Jazz to her senses, causing the jacket and scarf she was wearing to loosen out, making her come to her senses. Johnny sends his Shadow to distract Danny while he forcefully slips the ring and clothes back on Jazz, then forcefully makes her push the genetic lock button to open the portal where Kitty awaits. There, she absorbs the power to take over Jazz's body. Danny goes ghost and manages to take out the ring, causing the takeover to cancel itself out. Danny flies off with the ring and the Shadow gives chase.
Elsewhere, Tucker grows sick of the goth look and decides his original role as a techno geek is much better suited to himself, something which Sam agrees to, having used reverse psychology to return Tucker back to the role he was meant to be in. They then get a call from Danny who needs Tucker's help. Back at Fenton Works, Johnny locks up Jack and Maddie in their own room when they wake up, only to be freed when Danny flies through the door and the Shadow follows. Danny flies to the basement and gets the Shadow to destroy the Genetic Lock machine, closing the Fenton Ghost Portal. Angry, Johnny and his Shadow reunite and give chase to the Ghost Boy. Danny lures Johnny's Shadow to a stadium where with Tucker's help, manages to light up the entire place making the Shadow disappear and for Danny to suck up a helpless Johnny. Jack and Maddie come afterwards, disappointed in not being able to deliver their own blow to him.
Jazz gives thanks to her brother while Jack and Maddie admire Danny's similarity with them. As a reward, Jack gives Danny one of his jumpsuits which is obviously too oversized for him to wear by school the next day. Unfortunately this also makes him yet again a target for Dash and his friends, much to a relieved Tucker.
- Allusions: See List of allusions
- Goofs: See List of goofs
- At the start of the episode, Ember is seen in the Ghost Zone in a line leading to the Fenton ghost portal repeatedly being opened and closed by the DNA lock.
- This is one of the rare times Tucker is seen without glasses.
- When Danny takes the ring from Kitty, he calls Johnny "Freakshow."
- This was the last episode to premiere in 2004.
Click here to view the gallery.