Panicked Juliette, Monroe, and Rosalee enlist Hank's help in fending off a zombie hoard while trying to figure out what happened to Nick. Knowing the truth, Captain Renard takes measures to help rescue Nick from the clutches of his brother, Eric. Elsewhere, along with the help of the mysterious Stefania, Adalind finds herself facing her most gruesome task yet in her effort to regain her Hexenbiest abilities.
Monroe, Hank, Rosalee and Juliette track down a manic Nick and do all they can to find him and reverse what's been done to him before he causes any more damage. Meanwhile, Captain Renard does his best to clean up the zombie fallout on all fronts - domestic and international. Elsewhere, the more time Adalind spends with Stefania, the more disturbing things seem to get in her quest to regain her Hexenbiest abilities.
Series of disturbing crime scenes leads Nick and Hank to the resurrection of an old feud that's all too familiar for Nick and Monroe. With the news of a royal family member's demise, several key players start to make their move. Meanwhile despite his recent trauma, Nick finds himself healthier than normal and Monroe and Rosalee talk about moving their relationship forward.
When Nick and Hank investigate a drowning death with mysterious marks on the victim's ankles, they happen upon a group of water-bound Wesen with a deadly postcoital cuddle. Meanwhile, Rosalee starts unpacking her things at Monroe's, and Captain Renard makes a startling realization about the possible identities of the Royal Baby's parents.
Nick and Hank are on the case as repeat instances of apparent vigilantism have whispers of an old Spanish legend making their way through a working-class Portland neighborhood. Elsewhere, Juliette learns the truth about Nick's mother. Meanwhile, Adalind has a brief scare during her ultrasound.
Nick faces his toughest challenge yet when he and Hank investigate a case that combines religious phenomenon with the dark dealings of the Wesen Council. Meanwhile, Rosalee is torn when Nick's case challenges her Wesen loyalties. Elsewhere, Captain Renard leaves town to tend to some "family matters."
As a deadly crime spree begins to surface, a century-old urban legend takes shape in Portland's sewers and becomes Nick's latest case. In Europe, Adalind meets Prince Viktor, who's come to bring those responsible for his cousin Eric's demise to justice. Meanwhile, Captain Renard responds to the recent attempt on his life.
After a string of delinquent teens go missing, an old Wesen tale of an evil Santa who brings more than just a lump of coal may be the prime suspect. The investigation intensifies as Nick and Hank take things a little too far. Meanwhile, Monroe enlists Juliet to surprise Rosalee for their first Christmas together with unintended results. Elsewhere, Captain Renard's tour of Europe brings him closer to tracking down Adalind.
Nick and Hank investigate a Wesen "healer" whose ability holds risks that far outweigh its rewards. Meanwhile, Juliette takes in a friend when domestic issues escalate and Hank makes a move on his physical therapist Zuri. Elsewhere, Captain Renard finally tracks down Adalind and has a stern warning for her.
Nick and Hank are called to the scene of a gang-related homicide. The case escalates as Zuri, Hank's physical therapist, and her brother get caught up in the investigation. Meanwhile, Juliette seeks advice from Rosalee in dealing with the news that her friend is Wesen.
Nick and Hank are called to the gruesome murder of a veteran working in home security. During their investigation, they discover this might be one of several revenge killings regarding a horrifying cover-up involving members of the army and military contractors. On the domestic front, Monroe accompanies Rosalee during her long overdue reunion with her mother and sister. In Europe, Adalind sees hints of what she thinks might be her powers returning.
Nick and Hank investigate a cop killer who scalps his victims. Meanwhile, Juliette begins to communicate with Nick's mom via email and Adalind finds herself much closer to delivering her baby than she previously thought. Elsewhere, Monroe's parents decide to surprise him and Rosalee with an early arrival to Portland after learning some exciting news.
Monroe fights an impossible battle to convince his parents to embrace the life choices he's made. Meanwhile, Nick turns to Juliette to help him figure out the Wesen aspect of his cop-killing scalper investigation. On the Royal Baby front, Captain Renard learns new information that forces him to contact Adalind in the interest of keeping her and the baby safe from Viktor.
Horrible new predator creeps into Portland with its sight set on a young expectant couple who are close friends of Sgt. Wu. Nick and Hank must figure out how to deal with Wu as the investigation escalates. Meanwhile, Adalind prepares for a special delivery while her enemies are hot on her trail.
Nick and Hank find themselves thrown into the middle of an ancient battle and things heat up when the Wesen Council decides to get involved. Monroe and Rosalee fill everyone in on early Wesen history. Meanwhile, Sgt. Wu is still reeling from the events he recently experienced. As things heat up in Europe, one of the Resistance's most trusted allies gets compromised as he tries to protect Adalind.
Double homicide leads Nick and Hank to a traveling carnival where the performers are not what they seem. To get a better understanding of what's going on behind the scenes Monroe and Rosalee go undercover. On the wedding front, Monroe has a really important question for Nick. In Austria, an invaluable member of the Resistance makes the ultimate sacrifice to help Adalind.
The Resistance's plan to keep Adalind safe gets kicked into high gear when an unexpected ally arrives to ensure she and the baby make it out of Europe safely. In Portland, as Monroe and Rosalee prepare for their upcoming wedding, Nick and Juliette are reminded of their failed proposal.
Nick and his mom, Kelly Burkhardt, join forces to protect Adalind's baby. Meanwhile, Prince Viktor activates a deadly stateside asset to find Adalind and her child.
Nick and Hank investigate a dangerous female suspect leaving a trail of Wesen in her wake. Elsewhere, Adalind takes measures into her own hands, even if that means forging a dangerous alliance.
Nick does his best to educate Trubel on how best to handle the world she is learning about for the first time, and decides it best to bring her on a ride along with Hank. They find themselves investigating the homicide of a young woman that strikes a chord for Trubel. Meanwhile, Adalind makes a discovery that she hopes will lead her to regain something she has lost.
Nick and Hank are called to investigate a double homicide, and quickly learn the victims were from a special section of the Verrat tasked with finding rare objects pertaining to the Wesen world. Trubel gets involved with a mysterious father-and-son tandem that crossed the country in a desperate attempt to deliver invaluable cargo to "the Portland Grimm." Meanwhile, Captain Renard begins to grow suspicious of Adalind's recent behavior and quietly decides to put extra eyes on her.
It's Monroe and Rosalee's big day and their joy will only be matched by unexpected heartache for those around them. Nick and Juliette make a startling realization that could shake their relationship to its core. Meanwhile, Adalind proceeds with a delicately laid plan that leads to a catastrophic event that will alter the course of Nick's journey.