Pete Davidson returns as Nolan's brother in the opening of the episode, pulling a prank on him before asking to stay over. Chen tries to help Tamara decide her Halloween costume, though Tamara thinks they're all lame.

Chen's neighbor comes knocking on their door in a panic, knowing someone is getting scammed. She moves to investigate only to find an elderly woman named Ms. Crouch trashing the supposed robbers' equipment-- it turns out they are ghost hunters.

At the daily brief, Grey reminds everyone that anything could happen due to it being Halloween. This is represented by the acronym "A.C.H." Nolan and Harper end up riding together for the day instead of being placed with Thorsen.

Nolan's brother's girlfriend Chasity ends up calling Nolan believing that he is missing-- only for Nolan to reveal he is actually in LA. This does not please her, leaving her to spew out a string of threats towards the younger sibling.

Chen and Bradford hand out candy to children, discussing Chen's mother's decision to make an appointment to freeze her eggs. Bradford compares her mother's actions to an insurance plan for a car wreck, leaving Chen to laugh at his poor choice of words. Before their conversation can be taken any further, a mother frantically rushes in claiming she cannot find her child.

The two attempt to mediate the situation by asking another child, named Alton, questions about where he lives, his father's name, etc. It turns out to be a poor attempt as the child knows nothing that will help them. Meanwhile, Nolan is arguing with his brother about telling his girlfriend where he currently is.

Harper and Nolan pull into a scene in which people are running, though it is unsure as to why. It's not until Nolan is rushed by an intoxicated girl that they realize the situation. She's under the influence of a new designer drug, making its users something akin to zombies.

Returning to the accidental abduction, Bradford and Chen go to Alton's home to find the other missing child. It turns out to be a case of an accidental switcharoo between two children in the same costume.

Lopez ends up investigating the two ghost hunters. They attempt to convince her what they do is legitimate, despite looking like a very valid elder fraud case. This involves the two showing Lopez graphs and video evidence-- of course, she does not believe them.

Pete reveals that his girlfriend is pregnant, leaving Nolan to get angry at him. They have a poignant talk about how their dad left Nolan, and how he shouldn't do the same to his child. On the other end of the spectrum, Bradford and Chen continue to talk about potential children.

Nolan and Harper go speak with the woman who rushed them, she is now conscious. They ask what kind of drug she took, wanting to get answers out of the rather lifeless victim. The drug had irreversible damage to her nervous system and brain function, explained by the doctor before being interrupted by more users being wheeled into the hospital.

It's revealed that the new drug is called BombX, sold exclusively on ClipTok. The team decides the best call is to use the hashtags to track the dealer down before it's too overwhelming.

Nolan asks Pete to help the team track down the drug on ClipTok-- comically, Pete pulls up the dealer in little to no time. Lopez believes Ms. Crouch and tells Chen and Tamara that their building is haunted. Harper goes trick-or-treating with her ex and daughter in Star Wars-themed outfits.

While dressed as Bonnie and Clyde, Chen and Tamara discovered why their bathroom is so cold. Thanks to Lopez, Tamara believes it to be haunted though Chen believes it's something else. Turns out there is a secret hallway behind their bathroom mirror.

Pete ends up being the decoy buyer for the dealer on ClipTok and Nolan promises to look out for him.

Chen and Tamara discover that it wasn't a ghost living in their walls, but rather a squatter with a taste for stalking. Margaret, their neighbor, is in danger as the stalker living in the walls is right behind her. Chen makes it out to save Margaret just in time, knocking out her stalker before he could do any harm to anyone.

Pete ends up successfully obtaining the drugs for Nolan and Bradford before the two pursue the dealer on the way to his supplier. Nolan and Bradford decide to go after the supplier instead of waiting for backup on a busy night.

The two uncover a cult-like theatre where many of the users of BombX seem to be and arrest two suspects. Nolan ends up being attacked by one of the users before accidentally throwing him over a balcony in an act of self-defense. After checking their pulse, the man is still alive before both Bradford and Nolan taze him.

Harper and her ex-husband end up waking up next to each other-- they aren't too sure how to handle the situation. Donovan speaks on how he was about to propose to his new girlfriend, though he seems to have doubts due to the previous night with Harper.