At a launch party for the surefire hit video game Black Forest 2, two of the developers, Jenna and Brody, sneak off into an upstairs office to "celebrate" their hard work. But when Jenna feels like she's being watched, she stops undressing and goes back to the party. Within moments, she hears a scream coming from the office, and when she returns, Brody's body is cut in half. Somebody killed him.
At the crime scene, Nick and Hank examine the severed body and the bloody writing on the wall that reads, "Play my game." When they interview Dominick, the head of the game's company, they find out about Black Forest 2's code, a groundbreaking algorithm that allowed hundreds of players to play online at the same time. It's enough of a proprietary asset that all involved stand to make millions. Suddenly, the killer calls from inside the office building, reiterating the cryptic message he painted on the wall. But when the cops check the location of the call, the room is empty... that is, except for three pieces of title paper from popular fiction.
Juliette has become so aware of her own paranoia that she's borderline obsessed. One night, as she's trying to sleep, Juliette awakes to see a ghostly version of Nick standing in her bedroom, soaking wet. He disappears before she can figure out what he wants.
The killer seems to be very tech savvy, since he shut off the building's security cameras when he committed the crime. Nick asks Monroe if he knows of a Wesen that can cut people in half using acid, but it doesn't seem to ring any bells. The game company's Dominick calls Nick with a lead - he fears Jenna's ex-boyfriend Ridley Cooper might have something to do with the crimes. Nick plans to pay the guy a visit.
Juliette visits Monroe and Rosalee at the Spice Shop to tell them her visions are getting clearer. When she mentions her vision of Nick, Monroe informs Juliette that on the night of her coma, Nick and she were both soaking wet from standing out in the rain. Rosalee thinks Juliette's regaining her memory! Juliette doesn't want Nick to know, since she thinks he's trying to keep her in the dark about some things - mainly the Grimm world. Rosalee and Monroe agree to come to Juliette's house to help her figure out what all her visions mean.
Nick and Hank interrogate Ridley Cooper at his apartment, where they find out a lot about how Black Forest 2 works. Ridley and his sister are video game testers, so they've been playing the game for a while. Their game logs provide an alibi, but Ridley reveals something interesting: Brody's character inside of the game died three hours before he was killed in real life... and in the same manner. The person that killed him is named "Nameless" in the video game world.
Meanwhile, Renard receives a mysterious phone call from a castle spy in Vienna; it's urgent they meet in person soon. When Renard arranges a meeting at the Lotus Cafe, his castle spy informs him that his brother and the other six families are arranging the dissolution of the Union. They want to take complete control of the power, by any means necessary. As the two talk, Renard notices a shady figure enter the bar, drop a briefcase and leave. Renard runs to grab the briefcase and tosses it out the door just as it explodes in the air. He's shaken, but okay. Outside, Renard shoots the man who brought in the briefcase and kills him. It's Martin Pourtales from the E.U. It seems the Royals will stop at nothing to get what they want.
Back at police headquarters, Sgt. Wu discovers the three title pages from popular fiction that the killer teased them with all have authors with nom-de-plumes - or pseudonyms. The killer is continuing his "guess my name" riddles. Nick and Hank decide to virtually stake the guy out - they're going to go inside the game and follow the "Nameless" character's moves. Maybe he will lend some clues to his next possible victim.
Dominick helps Nick and Hank get Nameless' IP address by tracking him in the game. As they're watching, Nameless cuts another character in half - just like he did to Brody in real life. The character is Vicky Edwards, another one of the game's programmers. Nick and Hank rush to her house, but they're too late. The killer morphs into a Fuchsteufelwild and cuts the girl in half with his acid spewing claws. On the wall, he writes, "Guess my name." Before leaving, the killer gives the police another riddle - this time, a Sudoku with highlighted numbers.
Back at the precinct, Nick solves the Sudoku riddle - it's a date and a time. Since the killer called Jenna before his second murder, they bring her in for questioning. Under duress, Jenna admits that she stole the groundbreaking code from a random tech guy who helped reboot her team's computers one late night at 4:00 a.m. That technician asked Jenna out on a date, but she blew him off, didn't even remember his name or face. After her team took all the credit for his work, it seems the killer came back for revenge. With the truth revealed, Nick and Hank go to the trailer for information on Fuchsteufelwilds. Nick realizes all the names of these creatures in the history of the Grimm world use the same cluster of letters.
Using an anagram solver and a list of every player in the Black Forest game, Nick finds out their suspect is named "Trinket Lipslumbs." Nick devises a plan to capture the killer, but they need to use Jenna as the bait. In her apartment, Jenna plays Black Forest and runs into "Nameless" in the game. Jenna, now knowing his name, catches Trinket off guard and kills his avatar. He gets so angry he locates her coordinates and rushes to her apartment to kill her; only the police are waiting for him this time. When Nick chases him to the rooftop, Trinket refuses to "lose" and jumps off the building to his death.
Monroe and Rosalee have dinner at Juliette's house. As Monroe and Rosalee explain how they met, Juliette has another vision of Nick, this time he seems to be looking inside of a book very closely, eager to find something out. Before she can find out more, Nick's apparition disappears. Monroe realizes she's seeing Nick inside of the trailer and then stops talking because he's said too much. Juliette gets it now; she was at the trailer the night of her coma! She begs him to take her to the trailer, saying if he won't let her remember Nick, she'll just forget him altogether. Later on, Monroe tells Nick that Juliette wants to see the trailer and is threatening to leave Portland if she isn't taken there. Nick has a choice to make.