Episode 4 of The Spiderwick Chronicles kicks off with a thrilling scene where Jared manages to capture Thimbletack using a clever mouse trap. Elsewhere, Dr. Brauer's neighbor storms into his garden, furious about her pets collapsing and plants wilting. As she storms out, Jared sneaks in and tags a menacing "Beware" sign on the doctor's door.
Meanwhile, Simon's heart goes out to Thimbletack. He gathers berries and other offerings, hoping to strike a peace deal with the creature. Jared, however, remains suspicious of Calliope, whom Simon has taken a liking to.
Back at the Spiderwick house, Hatcher and Emiko arrive to assist with Thimbletack's case. The creature reveals that Lucinda is alive but fears leaving the "protection" of the Spiderwick estate. Jared's skepticism drives them away, but Simon stays behind.
Later, Bree arrives at the Spiderwick house expecting a sparring session. Instead, she throws a raucous party, justifying it as a way to loosen up Mallory's "uptight" attitude. It transpires that Bree's father, Tanner, a real estate agent, plans to shut down the psychiatric hospital. Helen steps in to defend Dr. Brauer and the hospital.
At home, Simon shares what Thimbletack has told him about a magical circle leading to the realm of the elves. He believes Lucinda is trapped with the elves after making a deal at the Goblin Market. Thimbletack offers information on four vaults in Henson as a sign of truce. They divide the map and rush out to retrieve the hidden pages.
Jared and Emiko ventured into the hospital's shadowy corridors, successfully retrieving one of the precious pages. Meanwhile, Simon and Hatcher braved the abandoned auto factory, its rusted remains echoing with forgotten memories. After Hatcher departed to seek the vault's secrets, Calliope appeared before Simon, her voice trembling as she revealed that Mulgarath was not her father. She poured out her heart, sharing the tale of how humans had destroyed the environment, leaving iron structures as monuments to their folly and murdering the fae. Simon, the epitome of kindness, felt a deep empathy for her plight. He also discovered that the twins' secret language was a pidgin version of the fae's ancient tongue.
At the psychiatric hospital, Grace stumbled upon a towering painting that narrated the legend of Henson and the Meskwaki tribe. According to the legend, the Meskwaki tribe had warned the new settlers against the evil that lurked in the shadows. They believed in the existence of the wendigo, a beast with an insatiable hunger that devoured everything in its path. During a feast, the settlers' gluttony led to their doom, as 200 of them perished and became a meal for the wendigo. The remaining settlers were miraculously saved by the tribe, and in their honor, the hospital was named after them. Dr. Brauer, privy to this tale, pretended ignorance, his eyes betraying no hint of recognition.
Emiko and Jared found solace in their shared isolation, bonding over their struggles to forge friendships. They reluctantly decided against venturing into the treacherous troll territory, where another page awaited. Meanwhile, at Dr. Brauer's home, he invited his neighbor for a snack he had prepared. But once she tasted it, she couldn't stop eating, her appetite seemingly bottomless. With a twisted smile, Dr. Brauer confessed to the murders at the feast and revealed his sinister plan to grow dragons that would slay everyone in the town. The dragons' poisonous breath tainted the earth, seeping into the water system, causing the townsfolk to fall into a deep slumber. It was during this chaos that Mulgarath plotted to devour the unsuspecting citizens.
Jared returned with Emiko to find Thimbletack unexpectedly free. Simon revealed the secret behind their twin language, and together, they followed the recipe to grow the mushroom circle, hoping to find Lucinda. But instead of summoning her, they unwittingly angered a sprite, which threatened to wreak havoc. Thimbletack's deceit was revealed as he vanished into the shadows, leaving them to deal with the enraged sprite.
At the party, Mallory was paired with a boy who later turned out to be Bree's boyfriend. Bree's motivations for this setup remained a mystery, and Mallory's confrontation with her yielded no answers. As the spite created a commotion, Jared, instead of trapping it, lashed out with a pan, his impatience getting the better of him. This led to a heated argument between Simon and Jared, ending in a fistfight that saw Jared striking out in anger. Simon, hurt and disappointed, stormed out.
Helen's arrival brought more chaos as several students, including Emiko, mysteriously fell asleep and were rushed to the hospital. Mallory, determined to find Bree, ventured inside and spied her whispering to the sprite, reviving it and setting it free. Meanwhile, Simon made his way to Dr. Brauer's and Calliope's abode, realizing that the doctor was none other than Mulgarath himself. The stage was set for a climactic confrontation that would test their friendships and reveal the true nature of their adversaries.
