NBC CEO Robert Greenblatt confirmed in early 2014 that the chances of renewing the series for a fourth season were very high thanks to the success programming show on Friday nights in the United States: "I think that the genre audience proves to be a very loyal one.

[4][5] In mid May, NBC announced its official TV show's premiered dates, among which is included the fourth season of Grimm that will air on October 24, 2014.

[9] Toni Trucks will appear as Deputy Janelle Farris in "Highway of Tears"; a sheriff who will help Nick & Hank with an investigation.

Meanwhile, the Grimm Diaries that Trubel owns in the guest room of Nick's house attract unwanted attention from Wu and Special Agent Chavez.

Nick and Hank investigate a vehicular manslaughter case where the driver turns out to be a rich heir being driven to madness by her Luison (Wolf-like wesen) quadruplet husband named Gabriel and his three brothers.

Trubel and Josh work together to track down the Wesenrein with gleichheit (equality) masks who keep threatening against Monroe and Rosalee's mischehen (mixed marriage).

An unsuspecting traveler brings a blood-sucking cryptid – the legendary "El Chupacabra" – to Portland, and Nick and Hank investigate.

Nick and Hank train Wu to deal with woged wesen, which allows him to confront Officer Jesse Acker, who is secretly a part of the Wesenrein, but without leverage, he cannot force him to turn on the group.

Juliette and Rosalee scour the wedding guest list, provided by Trubel, with help from Bud, to find anyone who would have exposed them to the Wesenrein.

Nick, Hank, and Wu investigate a shocking homicide of a ghost hunter at a supposedly abandoned residence.

Portland residents think it is haunted by a ghost; but Nick, Hank and Wu discover that an electric eel-like wesen called a Matanca Zumbido is responsible.

Juliette's startling revelation to Captain Renard leads her to a longtime family friend from his past, a mystical woman named Henrietta (Garcelle Beauvais).

Adalind pays Henrietta a visit to understand the extent of Juliette's powers but instead learns she is pregnant with Nick's child.

Nick and Hank investigate a crime scene in the middle of a bizarre love triangle involved a flatworm like wesen called huntha lami muuaji.

Captain Renard seeks Monroe and Rosalee's help to stop phantom bleeding when he was shot by Weston Steward.

Elsewhere, Captain Renard continues to suffer from mysterious bleeding and visions, while Monroe works toward coming to grips with the Wesenrein incident.

Nick and Hank newest investigation is on a homicide in the dark and mysterious path of a local Native American "vision quest" involved mishipeshu (underwater Panther).

Captain Sean Renard battles the darkness within and Nick finds hope for Juliette in the last person he expected: Adalind.

Nick and Hank investigate a grisly murder get closer to uncover the identity of the vicious serial killer while Wu's life is in grave danger.

After the shocking discovery of his mother's death, Nick is determined to get revenge and take the fight to the royals with Trubel's help.