Oh, Grimm. Only you could provide such a game-changing new character and then absolutely refuse to let her change the game until next episode.
Our gamechanger is Ms. Theresa Riubel, and if I may paraphrase Agents of SHIELD, "Someone really wanted her name to spell T.Rubel." Theresa is a young Grimm who doesn't know she's a Grimm or what Wesen are, just that monsters only she seems to be able to see keep attacking her and then she has to murder them. This has, perhaps unsurprisingly, made he a little crazy.
What we want, obviously, is for Theresa to spill her guts about her life and reveal some fascinating details about the other Grimms of the world, but instead we watch Nick and Hank slowly chase her down for murdering three Wesen (who, it should be mentioned, were all coincidentally already attacking her before they knew she was a Grimm). They only discover Theresa's Grimm-ness when she tries to kill a startled (and thus Woge'd) Monroe, and then they spend the rest of their time trying to convince her she's not crazy, culminating with a trip to Aunt Marie's trailer. And maybe next week we'll get a little info on what the hell is happening with Grimms that aren't related to Nick.
Meanwhile, in a plot twist no one could have foreseen, Renard's refusal to tell Adalind that he gave their child to the woman who recently protected her from evil Wesen royals instead of those same evil Wesen royals has led to troubl!. Adalind calls Prince Viktor (who is already back in Austria, which, grr) and says she'll do anything to be allowed to live with her baby, and Viktor instantly seizes the opportunity, asking Adalind to go do something evil with the Grimm blood she still has floating around in her system.
Renard does say that he can't tell Adalind the truth of who he gave the baby to because Adalind would never stop searching for her, which is complete bullshit because Adalind is never going to stop searching for the baby no matter who he gave Diana to. Maybe you could argue that it's better for Adalind to look in the wrong place for the baby so she can't find it, but 1) Adalind's not the problem, the Royals are, (actually, is there any reason Adalind couldn't have just gone with the baby and Nick's mom?) and 2) if she thinks Viktor has it it opens her up to working for Viktor, because Viktor is not a moron. Speaking of, he's also already figured out that the "Resistance" members who stole the baby from him are Renard and Nick and their posse, or at least they know where the baby is because Renard's been more or less part of the Resistance the entire time. Maybe Renard wants to stay in Austria so he doesn't catch all the stupid.
Other than the FBI agent from last time lurking around waiting to kill Renard, nothing else happens. Which is sad, because Grimm basically added Faith from Buffy the Vampire Slayer, and there's so much potential here! It's all just potential they wanted to save for next week, I guess.
• The episode start with Renard having written his daughter's name on a cocktail napkin in a very bizarre font. It's really weird.
• So I guess that black knight chesspiece Nick found at the first crime scene really was a random item someone left there? That's also really weird.
• Monroe is advising Nick and Hank on potential Wesen when they get called to the second crime scene, and when they all arrive, Wu asks Monroe what the hell he's doing there. It only takes a few seconds, but it still irritated the hell out of me because this nonsense could be completely avoided if they just brought Wu into team Grimm.
• Upon arriving at Nick's trailer, Theresa wisely refuses to go inside with Nick. I never quite realized how sexual assault-y the trailer looks. Good call, Theresa.
• Is it me, or is Nick's increasingly absurd demands of his friends getting hilarious? Sure, he's needed Monroe and Rosalee for Wesen info plenty of times, and then last episode they had to hide Adalind and Nick's mom, but it was kind of an emergency. Now a furious Adalind is literally knocking on their door and Nick asks them to babysit her merely so he doesn't have to deal with her, and later he brings Theresa home with him without even asking Juliette. I'm just saying, if I brought home random 16-year-old girls to stay for an indefinite amount of time, my wife would probably not handle it quite so politely.