Nick is reunited with his long-lost mother Kelly as they battle the Dragon Tongue killer. Afterward, Kelly explains where she's been and how the Royal Families threaten them all. Meanwhile, Rosalee and Eddie work to find a cure to Jessica's condition and Renard calls in help.
While Nick tries to duck a FBI investigation into the death of two of their agents, his mother Kelly goes to see Catherine and get the antidote to Juliette's condition. Meanwhile, Renard prepares to wake Juliette up on his own.
Hank's high school friend Jarold comes to him for help when his daughter Carly is abducted. Hank is unaware that Jarold is a Coyotl, but Nick soon realizes that Jarold is a Wesen and offers his help. Meanwhile, Juliette reacquaints herself with her old life.
As Nick explains the ways of the Wesen world to Hank, they're called to an accident scene that proves to be ground zero for an outbreak of a plague that only affects Wesen. Meanwhile, Renard gets word that the Families have sent another agent to Portland to recover the key, while Eddie and Rosalee go on a picnic.
A man of the cloth comes to the police claiming that an accountant has stolen from the church's bank account. However, when the accountant come up dead, Nick and Hank figure that the reverend is involved. Meanwhile, Juliette tries to cope with her situation with Nick, and the Family's assassin strikes.
While Nick and Juliette explore their new relationship, an old girlfriend comes to see Eddie and warns him that someone wants him dead.
A father with a vicious temper beats his wife and flees with his daughter. Nick and Hank investigate and soon discover that the father is a Wesen. Meanwhile, Juliette continues trying to remember more about Nick, while Adalind calls Renard and demands to know who killed her mother.
Songs: Hilary Grist -- Tomorrow is a Chance to Start Over
A decathlon high school student is brutally murdered and Hank and Nick suspect one of his classmates, who may be a Wesen. Meanwhile, Juliette and Renard have disturbing thoughts of each other and Eddie gets an unexpected visitor at the apothecary.
A mysterious woman in white abducts a boy in broad daylight and the police are called in. Nick soon discovers that the boy's abductor is La Llorona, a mysterious spirit that abducts three children each year... and kills them. Nick, Hank, and a former police detective must track down the spirit and stop her before it's too late. Meanwhile, Eddie goes overboard in celebrating Halloween and a woman warns Juliette that she will soon have to choose between two men.
Nick goes after a brutal serial killer who preys on Wesen and may be a fellow Grimm. Meanwhile, Juliette and Renard draw ever closer.
Hank realizes that a murderer that he captured seven years ago may have actually defended himself against Wesen, and convinces Nick to help him reopen the case before the murderer is executed. Meanwhile, Renard convinces Eddie to help him with his obsessive behavior.
Songs: Antonio Vivaldi -- Spring
Adalind returns to Portland to take revenge on Renard and her mother's killer, as well as recover the key from Nick. To do so, she attacks Hank and manipulates Juliette into revealing the location of Marie's trailer.
After learning that Renard has been playing him since he became a Grimm, Nick sets out to settle the score between them. Meanwhile, Rosalee returns to town and helps come up with antidote for Juliette's condition, and Renard and Adalind form an uneasy alliance.
After Nick recovers from the purification process, he and Hank deal with three Wesen bank robbers who are using their true faces as "masks" to disguise their identities during their crime sprees. Meanwhile, the Wesen community is up in arms about the violation of their code of secrecy, and turn to Rosalee for help because of her family's connection to the Wesen Council. And at home, Juliette tries to deal with a series of hallucinations brought on by Rosalee's attempts to cure her and Renard of their magically-induced infatuation.
While trying to work out the ramifications of his new alliance with Renard, Nick investigates a murder where the victim was blinded with parasites sprayed into her eyes. Meanwhile, Juliette's hallucinations become clearer, and Adalind asks for help with her pregnancy.
A Wesen killer capable of severing its victims in half with its acid-covered claws goes after a team of programmers for a new online game. Meanwhile, Juliette asks Rosalee and Eddie to help her with her visions, and Renard meets his spy face-to-face.
While Hank and Nick investigate a Wesen lawyer who is using his abilities to tamper with a jury, Juliette seeks out help for the onslaught of memories she's experiencing.
With Hank on vacation, Nick turns to Renard for help when a fiery Wesen starts incinerating his victims. Meanwhile, Juliette learns of way to cope with her memories of Nick, and Adalind meets with a Gypsy queen to assess the value of her child.
With Hank still on vacation, Nick investigates an alien sighting that led to a cattle mutilation... and the death of a ranch hand. Meanwhile, Juliette comes to Eddie for help when she remembers that Nick is a Grimm.
Juliette's attempts to reconcile with Nick go awry when he falls under the influence of a Wesen that can inspire men... and drive them mad with obsession. Meanwhile, Eddie and Rosalee help Juliette remember her past with Nick.
A corpse comes back to life in the middle of a murder investigation, and Nick and Hank soon discover that a Wesen who can create zombies is at large in Portland. Meanwhile, Adalind finds herself negotiating with Stefania only to make a mortal enemy of Frau Pech, while Eric travels to the U.S. to fulfill the Families' plan. And Juliette convinces Eddie to show her his true face.
Zombies threaten to overrun Portland, and Nick discovers that Renard's half-brother Eric is involved. In Austria, Frau Pech attempts to win her battle against Stefania and obtain Adalind's unborn Royal child.