Eric and the Baron try to smuggle a comatose Nick out of the country, but the Grimm wakes up and lashes out at his captor. Meanwhile, in Europe Stefania instructs Adalind in how to recover her Hexenbiest powers.
Eddie , Hank, Rosalee, and Juliette finally locate Nick and manage to subdue him and give him the antidote for the zombie drug. As they wait or him to recover, Renard risks incriminating himself and the others to cover Nick's tracks during his rampage. Meanwhile, in Europe Adalind continues her trials to regain her Hexenbiest powers.
Nick goes back on duty and is immediately assigned investigate a case where the victims have burst open due to bloat. Things take a turn for a worse when Nick and Hank learn that all of the victims were Blutbad. Meanwhile, Renard deals with the aftermath of his brother Eric's death.
When one boy is drowned and another narrowly escapes, Nick and Hank investigate reports of underwater creatures and find a family of aquatic Wesen. Meanwhile, Juliette reads a cryptic email sent to Nick and Renard learns what Adalind has been doing in Vienna.
A Wesen vigilante is responsible for the brutal slaughter of two robbers, and Nick and Hank discover that an old Spanish legend of "El Cucuy" may be involved. Meanwhile, Nick tells Juliette the truth about his mother and Renard takes an interest in Adalind's ultrasound.
Nick and Han investigate an apparent case of demonic possession when an exorcism goes bad and a monsignor turns up missing. They soon discover the incident is tied to a Wesen legend... one the Wesen Council wants destroyed for good. Meanwhile, Renard flies to Vienna to deal with the aftermath of his brother's death, and Adalind receives a mysterious summons.
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 Juliette 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.