Nick and the police department goes on the hunt for a mysterious wesen woman who first seduces men and then gruesomely murders them in a "Arachnid"-related death.

When Nick consults him about an erratic murder committed by athletic ex-con Dimitri Skontos, Monroe soon helps him realize that's actually a victim of 'gladiator games' organized by the most bloodthirsty pride of Löwen, a lionesque feral species. Nick spends his anniversary working out the fighters are recruited through a dodgy parole officer and where the arena is hidden. Captain Sean Renard realizes the lucrative fights are becoming too notorious, his royal order to close down the games is ignored, so he turns to a priestly enforcer. Meanwhile first Monroe, then Nick go undercover, only to end up caged and hence in the ring, facing daunting ferals.

Nick investigates the robbery of a spice shop, that is owned by wesen, discovering that the thieves were after a dangerous drug.

A Schakal Wesen wreaks havoc while searching for the ancient Zakynthos gold coins, while a mysterious woman in black tracks his movements. Nick informs a dubious Juliette of his heritage just before she collapses and is hospitalized because of a poisonous scratch from Adalind's cat.

After their face-off with Kimura, Nick finds himself trying to come to grips with the return of his mother, Kelly Burkhardt. A trail of brutal murders unveils a foreign conspiracy to hunt down Nick, leading to several revelations about his past. Meanwhile, Juliette still lies in her mysteriously-induced coma as Rosalee and Monroe work tirelessly to bring her out of it safely. Elsewhere, Hank struggles with the shocking truths he's recently seen and Captain Renard deals with unexpected family issues when his estranged brother comes back into his life.

Park ranger Ryan Gilko is the first of several Wesen, affected by a contagious disease, who suddenly commit violent attacks on people. The team felt relaxed now Hank is being included in the secret, so Monroe takes Rosalee on a picnic. Alas, the plague spreads and even affects her, so it's up to Monroe to make the remedy they researched together while Nick holds her feral state in check. Captain Renard meanwhile learns that another terrifying European fugitive has arrived in Portland.

Even Nick is puzzled by the case of two murdered teenage favorite candidates to the high-school general knowledge quiz qualifying for the state competition. Wesen in the story belong to several species, one extremely rare. Captain Sean Renard wins a community prize and turns to Monroe for a medicinal cure for his sexual obsession with Juliette Silverton. Surviving competitor Pierce Higgins is actually an unwitting Wesen cross breed. In Vienna, Renard's brother, Prince Eric, confides unto his latest conquest.

On Halloween, Nick and Hank search for a figure from Mexican folklore who might be abducting children; meanwhile, Monroe tries to deal with some troublesome trick 'r treaters.

Nick is puzzled by several cases where a suspect who escaped the police is violently dealt with by a masked, cloaked avenger. He even leaves Nick messages, suggesting he is a 'real Grimm' who is cleaning up 'weakling' Nick's messes. But he strikes terror even with gentle Wesen, like the beavers, who seek help through Monroe, who fears it's a descendant of a medieval Grimm vigilante order. Nick suspects a police mole.

Monroe's potion finally relieves Renard and Juliette's passionate obsession, so he and Nick can collaborate again, even closer then ever, with Monroe and Hank aboard, against the royal conspirators. Three youngster Wesen, Cole Pritchard, his girl Krystal Fletcher and his former cell-mate Gus, repeatedly commit robberies using their Wesen appearances as if masks. Monroe witnessed a bank robbery and alerts Nick's police team as well as the 'Wesen Council', as this is a blatant violation of the centuries old Schwaben code, which Amsterdam HQ chief De Groot orders enforced. Juliette has novel supernatural experiences at home.

A mysterious drug related force begins to turn residents of Portland into feral zombies, meanwhile, Juliette learns more of the wesen community in the spice shop.

Nick's destiny is uncertain as zombies continue to overrun Portland.

When investigating a series of brutal murders committed on criminals, to Nick it appears that the culprit may be a character from a Latino legend.

Nick (David Giuntoli) and Hank (Russell Hornsby) investigate a Wesen "healer" whose ability holds risks that far outweigh its rewards. Meanwhile, Juliette (Bitsie Tulloch) takes in a friend when domestic issues escalate and Hank makes a move on his physical therapist Zuri (guest star Sharon Leal). Elsewhere, Captain Renard (Sasha Roiz) finally tracks down Adalind (Claire Coffee) and has a stern warning for her.

Nick (David Giuntoli) and Hank (Russell Hornsby) investigate a cop killer who scalps his victims. Meanwhile, Juliette (Bitsie Tulloch) begins to communicate with Nick's mom via email and Adalind (Claire Coffee) finds herself much closer to delivering her baby than she previously thought. Elsewhere, Monroe's (Silas Weir Mitchell) parents (guest stars Dee Wallace and Chris Mulkey) decide to surprise him and Rosalee (Bree Turner) with an early arrival to Portland after learning some exciting news.

A horrible new predator creeps into Portland with its sight set on a young expectant couple who are close friends of Sgt. Wu (Reggie Lee). Nick (David Giuntoli) and Hank (Russell Hornsby) must figure out how to deal with Wu as the investigation escalates. Meanwhile, Adalind (Claire Coffee) prepares for a special delivery while her enemies are hot on her trail.

Nick, Hank and Juliette learn what the Wesen Community already know, the Wesen were GODS in ancient Egypt Meanwhile, Adalind and Meisner again run for their lives after a tortured Sebastien reveals the location where he dropped them off. Sgt. Wu, still fighting for his sanity is visited by Juliette. She tells Wu of her ordeal, which seems to have helped him because Wu is later picked up and taken home by Nick and Hank.

It's Monroe (Silas Weir Mitchell) and Rosalee's (Bree Turner) big day and their joy will only be matched by unexpected heartache for those around them. Nick (David Giuntoli) and Juliette (Bitsie Tulloch) make a startling realization that could shake their relationship to its core. Meanwhile, Adalind (Claire Coffee) proceeds with a delicately laid plan that leads to a catastrophic event that will alter the course of Nick's journey.

The team scrambles to find a cure to get Nick's abilities back.

An unsuspecting traveler brings a blood-sucking legend with him to Portland, and Nick (David Giuntoli) and Hank (Russell Hornsby) find themselves investigating the gruesome trail of "El Chupacabra." Meanwhile, Monroe (Silas Weir Mitchell) and Rosalee (Bree Turner) prepare to leave for their long-overdue honeymoon as they are met with more threats regarding their marriage. Elsewhere, Viktor (guest star Alexis Denisof) and Adalind (Claire Coffee) decide to take a trip of their own, while Wu (Reggie Lee) decides to confront Nick about what he has been seeing.

The Wesenrein act on their many threats against Monroe and Rosalee's marriage. Meanwhile, Nick and Hank bring Wu to a place where he's sure to find the answers he's looking for. Elsewhere, Juliette tries to come to grips with her new reality.

Nick and Hank investigate a homicide they discover is linked to a wesen rite of passage.

As Hank and Nick get close to identifying a vicious serial killer, Wu's life is put into jeopardy.

Nick deals with his new home life as he tries to keep his child and Adalind safe.

A down on his luck Luchador receives a special mask that will make him the star he's always wanted to be. Misuse, however, leads to terrible consequences. Meanwhile, Eve believes something is amiss with Dixon's assassination.

Nick, Hank and Wu searches for a wesen killer who can liquefy human bones; Hank encounters an old flame.

Wu discovers he is infected with lycanthropia after being attacked by a Skalengeck from Black Claw. Trubel returns and Adalind leaves Nick to join Renard/Black Claw in order to protect not only her children but Nick as well.

Nick leans on Monroe and Rosalee as he worries that he may lose everything as he continues to battle Black Claw. Captain Renard ramps up his campaign as election day nears.

The war with Black Claw escalates as Nick and his friends are targeted for elimination.

Captain Renard vows to kill Nick following the massacre in Nick's loft.

Hank and Wu find a solution to stop Renard while Nick is still fleeing. Adalind gets a phone call that throws her into the middle of everything. Monroe's and Rosalee's babysitting adventure turns interesting as they witness Diana's power.

Nick devises a plan that will take Capt. Renard out of his element; Adalind and Monroe attempt to keep the plan on track; Eve and Rosalee race to get the spell ready in time.

A powerful Wesen named Zerstörer arrives in Portland, planning to do something with Diana. Nick returns to the house where he solved his first Wesen case to find a solution. However, Zerstörer is one step ahead of the gang.

Nick faces off against his greatest foe, yet as it seems no weapon can defeat him. Monroe, Rosalee and Eve search for answers that may help them in the fight. Renard and Adalind try to keep Diana and Kelly safe