It appears Nomura has gotten her way: ANOTHER changeling has been chosen... and look who it is.
―Strickler to Bular

To Catch a Changeling is the seventh episode of Trollhunters.

Official Synopsis

Armed with an ancient troll-hunting tool, Jim and Toby set out to unmask the Changelings living among them. Claire makes Jim a tempting offer.


After Jim finds the Killahead Bridge has been moved, he must use a gaggletack (a horseshoe-shaped artifact that reveals the true nature of a changeling by physical contact) to find who in Arcadia is a changeling. If he touches a changeling with the gaggletack, they change from human form to troll form, so Jim and Toby go around the school touching everyone with the gaggletack to see who is a changeling.




  • The song that is heard in the scene of Dr. Muelas while singing is "Cielito Lindo".
  • Title: The title most likely refers to the TV series "To Catch A Predator".
  • The music heard during the series finale end credits can be heard during Jim and Claire opening up to one another just before Claire reveals the letter Jim wrote her in the previous episode.
    • Getting Crap Past the Radar: When Claire reveals Jim's letter in front of him, she mentions that Jim "has to battle monsters", and asks what kind of "monsters" Jim battles. Claire further asks if Jim is under any sort of trouble, and reassures him that if he should need to talk someone about "the monsters", she's willing to listen. It's fairly clear that Claire thought Jim might have major depression, if not suicidal tendencies.
  • Running Gag/Continuity: A troll attempts to eavesdrop on Blinky discussing secretive trollhunter information, with Blinky reacting with "Do you mind?" and the troll responding nonchalantly with "Whatever." This is shown in the previous episode, as well.
  • Error: When Toby calls Jim regarding his dental hygienist being a Changeling, Jim's phone is seen on his right side. When Jim is seen hurriedly collecting his belongings to leave the Nuñez Estate, he is not seen taking his phone.


Tales of Arcadia logo
Arcadia Oaks-pedia has a collection of images and media related to To Catch a Changeling which can be found at To Catch a Changeling/Gallery.
Part One
"Becoming: Part 1"- "Becoming: Part 2"- "Wherefore Art Thou, Trollhunter?"- "Gnome Your Enemy"- "Waka Chaka!"- "Win Lose or Draal"- "To Catch a Changeling"- "Adventures in Trollsitting"- "Bittersweet Sixteen"- "Young Atlas"- "Recipe for Disaster"- "Claire and Present Danger"- "The Battle of Two Bridges"- "Return of the Trollhunter"- "Mudslinging"- "Roaming Fees May Apply"- "Blinky's Day Out"- "The Shattered King"- "Airheads"- "Where Is My Mind?"- "Party Monster"- "It's About Time"- "Wingmen"- "Angor Management"- "A Night to Remember"- "Something Rotten This Way Comes"
Part Two
"Escape from the Darklands"- "Skullcrusher"- "Grand Theft Otto"- "KanjigAAARRRGGHH!!!"- "Homecoming"- "Hiss Hiss, Bang Bang"- "Hero with a Thousand Faces"- "Just Add Water"- "Creepslayerz"- "The Reckless Club"- "Unbecoming"- "Mistrial and Error"- "In the Hall of the Gumm-Gumm King"
Part Three
"Night Patroll"- "Arcadia's Most Wanted"- "Bad Coffee"- "So I'm Dating a Sorceress"- "The Exorcism of Claire Nuñez"- "Parental Guidance"- "The Oath"- "For the Glory of Merlin"- "In Good Hands"- "A House Divided"- "Jimhunters"- "The Eternal Knight: Part 1"- "The Eternal Knight: Part 2"
Community content is available under CC-BY-SA unless otherwise noted.