In the dead of the night, two security guards at the Portland harbor stumble upon a gruesome scene inside a shipping container; it appears that two stowaways have been ripped to shreds, their mangled body parts scattered in pools of blood. Before they have time to consider what monster could have caused this mess, an attack from above from a saber-toothed tiger-like creature leaves them to the same fate. This isn't your average Wesen; this is something much, much more troublesome.
Meanwhile, Nick fights off Kimura in his home, with the help of the mysterious woman in black who arrives on the scene in the nick of time. After Kimura is rendered unconscious, Nick locks eyes with the woman and realizes that she is none other than his presumed dead mother. All he has time to learn is that his mother is, in fact, alive, and has been hunting down those responsible for Nick's father's death. Before she can explain any further, the police arrive on the scene, and she disappears into the night.
Meanwhile, Monroe and Rosalee are doing their best to find out what was responsible for putting Juliette in a coma. Rosalee works on a potion to test the chemicals in the cat's paw that scratched Juliette. When the formula turns blue, Rosalee realizes this is a sign of the worst: they need to get a memory-loss potion in the works, and they need to contact Nick immediately.
After the police clean up the scene and Nick explains that he took Kimura down on his own, Nick's mother shows back up and provides Nick with some further clarification. She needs to get her hands on Kimura because he's the last man alive who knows the truth about her being alive. Her friend died instead of her in the car crash along with Nick's father.
The family reunion is interrupted by the arrival of Monroe and Rosalee. Nick's mother immediately attacks, as is her Grimm impulse when she comes across a Wesen. But Nick stops her, explaining his unconventional relationship with Monroe and Rosalee. The two share their reason for visiting: Rosalee's cracked the code, and they need to stop Juliette's memory loss immediately. She can create a potion to do this, but it's extremely time sensitive and needs to be applied immediately. Nick tells them to hop to it, and they leave Nick and his mother to their not-so-warm reunion.
Nick wonders where his mother has been the past eighteen years? She claims it was all in Nick's best interest; the only way she could protect him was by keeping him as far away from her as possible. She went after those responsible for killing her husband and her friend, and became involved in the fight against the royal families who are trying to regain the control they had in the last century. Nick's mother emphasizes that the Coins of Zakynthos that Nick has in his custody need to be destroyed immediately; the sooner he gets them to her the better.
Renard isn't ignorant to the fact that Juliette's coma is a Grimm-related incident and realizes that the very vengeful Adalind was definitely involved. He arrives at Adalind's mother Catherine's house, explaining that Adalind's irrational actions were rash and idiotic. If Juliette dies, Nick could quit the force and leave Portland, and Captain Renard has put too much time and effort into Nick to let that happen. He needs to know what Adalind did, and Catherine admits that she may have a solution to wake Juliette.
Nick is called to the crime scene of the killing by the Mauvais Dentes, the horrible saber-toothed tiger creature. Nick knows something Grimm is afoot, but before he can put the pieces together, the case is taken out from under him by the Feds. Luckily, Nick has a new Grimm expert on his side to help him sort things out.
Nick takes his mother to Aunt Marie's trailer to do further research, a place she is apparently very familiar with. Nick uncovers the coins hidden deep in the trailer and hands them over to his mother, who explains that they can only be destroyed at the island of Zakynthos where they were forged. When Nick describes the puncture wounds on the victims of his latest crime scene to his mother, Nick's mother worries that the damage Nick encountered was the work of a Mauvais Dentes. The creature could only be in Portland for one reason: to hunt down Nick. She tells him to put the coins away for now; this is a serious issue that needs to be dealt with.
Meanwhile, the Mauvais Dentes sets up a trap that the federal agents fall right into. The ruthless creature slaughters one and holds the other hostage to lure in Nick. She calls Nick, begging him to come to a warehouse alone in order to save her life. Nick knows this is a trap he has no choice but to face, and he shows up at the scene with his mother in tow... two Grimms are better than one! When he arrives, both agents are dead, and a creature lurks in the shadows. Nick cautiously surveys the bloody scene, gun drawn, just as the creature attacks from behind! To be continued...