Wren's Halloween plans go awry when she's made to babysit her brother, who disappears into a sea of trick-or-treaters. With her best friend and two nerds at her side, she needs to find her brother before her mom finds out he's missing.
Sardonic Wren (Victoria Justice) hails from an unusually dysfunctional family. She can't wait until she escapes to college and leaves them all behind, but in the meantime, an invitation to the biggest Halloween party in the area at least offers her an excuse to get out of the house for a night. But when Wren is placed on babysitting duty so her mother can dash out and party with her handsome young boy toy, the dejected teen reluctantly takes her little brother Albert out for a night of trick-or-treating. Later, when Albert vanishes into a sea of costumed kids, his panicked sister enlists the help of her best friend April, wannabe womanizer Peng, and his charmingly geeky pal Roosevelt to track down her missing brother, and get him safely back home while their mother remains none the wiser. Meanwhile, over the course of one wild and unpredictable Halloween night, the group's frantic search lands them in some pretty outlandish situations, and provides Roosevelt with the perfect opportunity to impress his longtime crush Wren.
In Cleveland, Ohio, high school senior Karen "Wren" DeSantis' (Victoria Justice) opening narration describes Halloween in Cleveland as a time for its citizens to dress up and be less ashamed of themselves, citing the nickname "the mistake by the lake."Wren plans to attend NYU, which is where her dad studied. Her dad believed that college is where one finds their true self. Wren has a younger brother Albert, who is always cutting into her clothes. Albert is a young boy and has still not started talking.
Wren's widowed mother, Joy (Chelsea Handler), is dating a 26-year-old named Keevin (Josh Pence). Wren has her heart set on college life at New York University. Joy says that NYU is too expensive, and Ohio State is equally good.Her friend April (Jane Levy) has her eyes set on social status, and Wren's nerdy friend Roosevelt (Thomas Mann) has his heart set on Wren. The two girls are surprised when they find they are invited to a Halloween party by local heartthrob Aaron Riley (Thomas McDonell).Wren dresses up as Dorothy from the "Wizard of Oz", April goes as a kitty, while Albert dresses up as Spiderman with a torn-up arm. Wren is really looking forward to attending Aaron's party.
Unfortunately, on the night Wren is supposed to go to the party, she is commanded by her mother to take her 8-year-old brother Albert (Jackson Nicoll) trick-or-treating so she can go to a party with Keevin. Joy promises to sign Wren's NYU application if she can look after Albert for one night. The party that Keevin invites Joy to, turns out to be run by his friend Nate Brueder (James Pumphrey).Brueder was having a party at his house, with his parents in their room. Joy is disgusted with the behavior of all the young people in the party and accidentally enters Bruder's parent's room, and ends up spending some time with them.
At a haunted house later that night, Wren and April run into Roosevelt and his best friend Peng (Osric Chau) and they soon lose Albert.Albert wanders off and in turns meets a convenience store employee named Fuzzy (Thomas Middleditch) who seeks revenge against Jorgen (Johnny Knoxville), a mixed-martial arts fighter, who won the heart of his ex-girlfriend Lara (Abby Elliott). Fuzzy finds Albert sitting alone outside his store and takes Albert with him.Fuzzy and Albert go to Lara's apartment and tries to TP the place. But since it is an apartment block, he is unable to. He throws one roll into Lara's apartment which lands on a candle and catches fire. Fuzzy puts out the fire, but turns out the house belonged to someone else, who pulls Fuzzy in for a thrashing. Fuzzy's car is towed away with Albert in it. Albert gets off at a Captain Chicken outlet.At Wren's urging, Roosevelt asks his parents, two semi-eccentric pacifistic lesbians (Barb (Kerri Kenney-Silver) and Jackie (Ana Gasteyer)), to borrow their Volvo. When they refuse, he takes the car anyway. Wren touches Roosevelt's arm as a thank you for his help, and he almost has an orgasm.
Wren frantically searches for Albert all over town. She suspects that he might be at a local Captain Chicken restaurant on Euclid Avenue, a fictional pirate-themed fast-food chain. Again, they just miss him, almost running him over while fleeing local bully Mike Puglio (Patrick De Ledebur), whom they had challenged when their car died down in the middle of a busy street.Albert is then rescued by Denise (Riki Lindhome), a college girl dressed as "Galaxy Scout" (a fictional anime character).After Roosevelt accidentally destroys the restaurant's mechanical chicken statue (They ran into the bullies again and Roosevelt backed up the car in panic) and severely damages the car, April escapes (as she was desperate to get to Aaron's party). Peng challenges Mike to a duel and fires his loaded musket at him. Mike believed that Peng was bluffing and backs off when he finds that Peng's gun is loaded.
After being harassed and robbed of his candy by Jorgen at a party with Denise, and remembering Fuzzy's description of him (large man, with a tattoo of a dragon smoking a cigarette on his arm), Albert stows away in his convertible to seek revenge. Fuzzy sees Albert in Jorgen's convertible and follows him. Fuzzy rescues Albert from the convertible, after Jorgen goes into his house. Together they set fireworks on a bag full of dog poo outside Jorgen's house. Albert is not able to run away and is captured by Jorgen.
Wren, Roosevelt, and Peng drive off looking for him, and now April, who later calls from Aaron Riley's party with the false impression that she has found Albert. Wren, Roosevelt, and Peng arrive at the party, and the earlier duel with Puglio gives Peng some social acceptance.Roosevelt was about to express his feelings to Wren when Aaron starts singing a song about Wren. Wren is about kiss Aaron, when Roosevelt leaves the house. Wren follows him out, but Roosevelt leaves in his car.
Wren receives a phone call from Jorgen, who is holding Albert hostage at his house. He threatens to turn him over to the police for pulling the stunt with Fuzzy, unless she gives him a ransom of $400 in cash, which she doesn't have.
After Jorgen gives her his address, Wren desperately runs through the streets of Cleveland trying to find his house. Arriving and telling him she doesn't have the money; he calls the police but puts them on hold when Wren finds out that he is a fan of the Beastie Boys. She offers to give him the collectible jacket she inherited from her late father, which was left behind by Mike D in his recording studio, as a substitute for cash.
Jorgen seems interested in her offer, but he says he's still reporting them to the police. Then Fuzzy breaks in to rescue the boy and his older sister by throwing fireworks throughout the house. Jorgen is injured in the explosion.
Wren and Albert visit the cemetery where their father is buried and place a plastic pumpkin with flowers on his grave. Albert thanks Wren for finding and rescuing him, just before their mother picks them up and drives them home.
Roosevelt shows up at the house, stating that he will get a part-time job at Captain Chicken to pay off the damages that he caused, and declaring his feelings for Wren. Joy then takes Albert inside, allowing Wren and Roosevelt to share a kiss. Meanwhile, April wakes up to find herself in the arms of Peng and, after looking around for witnesses decides to make out with him again.
Fuzzy meets Denise, who asks him out on a date. He also reveals that his real name is Manuel. Later, Albert reveals that he secretly has been pulling prank phone calls on both his mother, sister, and his sister's friend for six months, which includes the uploading of a video to Wren's Facebook page, making fun of Wren's bug dance and "explaining rap".
