Brady has finally captured the monster of his dreams. Maxwell, Brady's dad, is horrified and a bit annoyed with his son when he discovers the beast; so he sets it free. Terrified, Maxwell incites the citizens of Ravenville to declare war against all monsters and to capture them in the forest. Luckily, Brady and his friend Virgil thwart the monster hunt by getting all of the town's children to adopt a monster. But not before he teaches them a lesson on the responsibility of monster pet ownership. Too bad for Brady that his monster does not come back to him.

10-year-old Stanley Crumb has captured a tadpole from Ravenville's infamous pond, the Black Lagoon. Poor Stanley had no idea the tadpole would grow into a creature so big; his fish tank can no longer contain it. Is it because Stanley overfed the poor thing? Things go from bad to worse when Stanley leaves the creature unattended overnight and he floods the basement. Brady and Virgil run to the rescue, but taming this beast is no easy task. Meanwhile, the snoopy Game Warden is obsessed with catching the Crumb family red-handed interfering with the local wildlife. Brady has a plan to catch the monster, as he wants to reunite the creature with its better half. To be a monster catcher, you sometimes have to be a monster matchmaker. Unlucky for Virgil, Brady has picked him to be the bait...

On his way home from work, a flu-stricken Maxwell meets Dr. Jekyll and Mr. Hyde. Delighted, Maxwell decides to put up Dr. Jekyll in exchange for his medical services. At first, the family finds it handy to have a doctor hang around the house. His medicated shampoo promises to help restore sheen to Brady's sister Arlene’s hair. Pollyanna, Brady's mother, is given a special powder to give her a radiant complexion. But his cosmetic concoctions have undesired, freakish side effects. Brady is very suspicious about the doctor’s orders. Brady realizes the doctor’s fiendish plan: the Plunkett family is slowly turned into mutants and is eventually sold to the local pet shop. While Brady attempts a daring monster rescue, his twin brother and sister, Marvin and Gaye, work on a reverse transformation formula.

With the help of his friends Ember and Virgil, Brady meets Vlad the Vampire and adopts him as his monster. He tries his to keep his new monster a secret, thinking that if his father does not notice the vampire, that he would let him keep it. Brady keeps getting weird calls from the citizens of Ravenville, complaining that the monsters are causing raucous. A secret meeting is held in the forest, with all the kids and their respective monsters: vouching it’s not their creatures who are responsible for this chaos. Brady and Virgil uncover an underground movement of the citizen’s neglected pets who are purposely sabotaging the monster’s reputation. As a confrontation mounts between citizens and beasts, Brady calls for understanding, to be responsible monster and pet owners.

Brady is distraught when he finds out that Maxwell wants to sell the house and move away from Ravenville. Brady is mostly devastated that he will never find his long lost favourite monster if he moves away. He promises a cash reward to whoever finds his beloved missing monster. Maxwell is stressed out by the sale of his property; he gets Brady to promise that the potential buyers will not be bothered by his beastly business. But much to Maxwell's horror, his open house is ruined since the monsters and their owners show up at the house in hopes of collecting the reward.

Mr and Mrs Dandy move from their tiresome old haunted house to open a ghost-free Bed and Breakfast. The Dandy children really miss their old haunted house; so Brady and friends agree to help out. Brady and Ember parade around as mock ghosts until Virgil finds and recruits new phantom friends to move into the inn. Much to the Dandy parents’ dismay, the journalists who came to review the new inn’s opening think the mock ghost gimmick is great fun. That’s until Virgil arrives with the real ghosts and scares everyone away. This gaggle of ghosts is bad for business. Even the Dandy kids admit that too many ghosts spoil the fun. The Dandy’s move again.

After witnessing a botched burglary, thanks to a helpful goblin, Brady comes home to find Maxwell and Pollyanna in a panic. They’ve heard that robbers are stealing valuable collectibles all over Ravenville. Their vintage comic books and childhood dollies are no longer safe from the greedy clutches of these hooligans. Maxwell frowns on installing a security system, Brady suggests using a monster as theft protection. Maxwell will not budge; he does not want a monster in his house! But after hearing Virgil’s appraisal of the comic book, Maxwell knows he’s sitting on a gold mine. So Brady hires the Werewolf to protect the family’s precious heirlooms. Brady's thrilled, he finally has a pet monster to call his own ... but does the rest of the family think it’s really a good idea to have a Werewolf around the house? Maxwell is so desperate to get rid of the furry fiend; he’s willing to put his beloved comic book collection up for bid.

Brady receives an email from someone claiming they’ve found his favourite monster. Brady takes a look at the enclosed photo – that’s him alright! Brady is ecstatic: his monster is staying with Matt from Vomit Falls and he’s willing to trade him in for another monster. Courting his father’s economical leanings, Brady suggests that they should drive down in their uncle’s motorized home to Vomit Falls for the family vacation. Sneaking Stitch in such a cramped vehicle will be tricky. Keeping him a secret from the other Plunketts, while on the family road trip from hell, will be worse. Especially when Brady has to find a replacement monster in the woods.

Brady has a webcast to demonstrate the technique for building a monster. Something goes wrong with the recipe, and his audience’s' projects turn into uncontrollable mischievous blobs. These blobs join together into one giant mega-blob, sliming up Ravenville and gobbling up citizens. How will Brady deal with this gelatinous problem and rescue his gobbled up friends? Brady gets the giant blob to swallow a mountain of every inflatable object in town, and then shoves a leaf blower into its side. The growing internal gas pressure launches the blob into the sky like a swelling balloon. Luckily it explodes over the water, making for a safe splashdown for the citizens who were trapped inside the blob. The mayor thanks Brady by having him clean up the tons of blob slime covering the city.

Max orders Brady: ""No more monsters in the house, or you lose your computer!"" Seconds later, a very hairy Yeti sneaks undetected into the Plunkett home, attracted by its favourite food - garbage. Brady stumbles upon ""Wigs"" the Yeti, and must now find a way to sneak him out before Max finds him. Virgil is there to help, but Arlene discovers their big hairy secret. She blackmails Brady into finding her a date to make her unappreciative boyfriend Bobby jealous. Brady ingeniously sets her up with a seductive Latin date - Wiggario. Arlene is smitten! Little does she know that Wiggario is none other than a shaved version of Wigs. Things get real crazy once Bobby, Arlene, Wiggario, and his Yeti nemesis confront each other.