When Chloe discovers that her new home's garden gnomes are not what they seem, she must decide between the pursuit of a desired high school life and taking up the fight against the Troggs.
Chloe and Catherine, her estranged mother, relocate to Tenderville, where they live in a huge home encircled by enigmatic gnomes. During dinner one evening, Chloe finds a mysterious green gem in a hidden room. She takes it and makes a necklace out of it. She unleashes a pack of ravenous and ravenous creatures known as "Troggs" in her basement by opening a portal from another realm without her knowledge. Chloe makes friends with Brittany, a popular girl at her new school, and her friends Tiffany and Chelsea, who are referred to as the BTCs. In an attempt to get into Brittany's social circle, Chloe grabs her attention with the necklace and hands it to her. Chloe comes across a Trogg at home and tries to kill it before it inexplicably explodes.
Catherine informs Chloe that she will be working an additional shift at work the following day. When the house gnomes find out that Chloe took the Keystone-the enigmatic green gem that Chloe ultimately gave to Brittany-they tie her up and reveal to her that they are still alive. The gnomes disclose that the Troggs are prevented from wreaking havoc in their realm by the Keystone. The Troggs became their mortal enemies after they ate the botanical lifeforms that comprised their way of life, according to Quicksilver, one of the gnomes. The gnome's current leader, Zook, also reveals that their previous leader, Zamfeer, once ventured into the Trogg world to destroy it but never came back. They used the Keystone to prevent the portals of the Troggs from opening. In order for Chloe to recover the Keystone, they ask her to repel the Troggs. Liam, Chloe's awkward neighbor and classmate, is also brought in to assist her.
At a school dance, Chloe intends to ask Brittany for the necklace, but she gets sidetracked while attempting to win over the BTCs. Chloe chastises Liam, who leaves because she fears their relationship will harm her social standing. Chloe devises a plan to drop by Brittany's house after learning that she forgot the necklace. On his way home from the dance, Liam unintentionally stumbles into a Trogg portal. When Chloe discovers Liam is telling the truth, she cuts off contact with the BTCs and leaves for home. Chloe regains her confidence after finding out where Liam is and follows him through a toilet portal. She meets Zamfeer and Liam, who accepts Chloe's apology with grace. In order to destroy the Trogg world, they find a giant crystal and devise a plan to blow it up using Chloe's phone's lithium-ion battery. They use the invading Troggs to escape through a portal, sucking all of the Troggs back into their realm after blowing up the crystal, which is a larger version of the Keystone.
Brittany shows up to further embarrass Chloe and Liam and destroy the remaining Keystone while the gnomes joyfully reunite with Zamfeer. The Gnomes, Chloe, and Liam watch as the Mega Trogg forms and escapes from the basement while Brittany reprimands her. Everyone is unable to flee, so they all go to the roof with an ooze plant, which the Mega Trogg is afraid of. Chloe destroys the Mega Trogg and returns them to reality by making a makeshift bomb out of the Keystone, Brittany's phone, and the ooze plant. As Chloe and her mother wake up together, Chloe tells her that she wants to stay, and Brittany affirms that she does not remember anything from the previous evening. After learning that the gnomes have also survived, Chloe and Liam walk to school together as friends once more.
