Anja Mittelmeier is the castellan at Castle Finster. She runs the gift shop and takes care of any needs of the guest.
In 2011, she helps orient Nancy despite her uneasiness that Nancy is staying at the castle during its Monster problem. Nancy soon learns that she used to date the castle's current owner, Markus Boehm, but Anja says dismissively that it was a long time ago. Though Markus was initially unhappy with the idea of his ex-girlfriend working at his castle, she does an amazing job at it, so they decided to be mature about the situation. She even helps Nancy navigate her own romantic problems with Ned.
Knowing that her nephew is clever and and partial to pulling pranks, she asks Nancy to be honest if Lukas is being too much of a pest. Though she loves her nephew and thinks of him as a good kid, she is fully aware that he's too mischievous by half and so won't hesitate to give him a stern scolding.
Eventually, Nancy stumbles upon Anja's resume as she investigates Karl's office. She calls Castle Cast, the place who recommended Anja, in order to learn more about her. They mention that everyone loved Anja and that she did a wonderful job getting the mail, inadvertently revealing that Anja lied on her resume. When Nancy confronts her about it, a nearly-tearful Anja laments that she really, really wanted the Castle Finster castellan job and lying on her resume was the only way a girl like her who hadn't gone to a fancy school could get it. She tells Nancy that she knows it wasn't the right thing to do, but she loves Castle Finster and works hard at her job. Seeing that Nancy isn't quite appeased, she promises to tell Markus the truth as soon as she's able.
As time goes on, Lukas is kidnapped by the Monster. A frantic Anja begs Nancy to find him, mentioning that she's looked everywhere and that this isn't like one of his usual pranks. Nancy does manage to find him after some time and helps him to escape the dungeon, but before she can escape herself, Nancy is knocked out and thrown down the dungeon's trapdoor.
However, a little thing like that doesn't stop Nancy for long and she's soon found a way out into the well maze. Unfortunately, every door is locked except for the one leading right back into the dungeons, which has a suspicious bag sitting near the exit. Rifling through it, Nancy finds extra supplies for the Monster's costume and an email from Markus, just like the ones in Anja's counter drawer. Looking more closely, Nancy sees that the email is a forgery meant to frame Markus. Once again entering the dungeons, Nancy comes face-to-mask with the Monster, whom Nancy now knows is none other than Anja.
Tossing aside her stifling mask, Anja fumes that she made Markus into who he is by constantly pushing him to make his mark on the world. But as soon as he landed his first big deal, he dumped her the very next day "for some stupid blonde". Humiliated and furious, Anja wants him ruined. Planning to do so by dressing up as the Monster and staging various attacks that would have eventually culminated in the death of a young woman (Nancy), Anja would have made it look like Markus had set the whole thing up as a publicity stunt gone wrong by using emails she had written and printed in his name.
Thinking fast, Nancy drops Anja down the trap door before she can do any more harm. Anja is then arrested, but not before swearing her revenge on Nancy.
- "There's nothing like love to bring order to a scattered world."
- "[Karl's] the victim of a joke alright, but it's more cosmic than practical."