NBC will air 'Grimm' season 4 episode 20 titled 'You Don't Know Jack' on Friday, 1 May, 8pm.Facebook/Grimm

The Nick Burkhardt (David Giuntoli)-Juliette Silverton (Bitsie Tulloch) relationship is likely to take a new turn in "Grimm" season 4 episode 20 titled "You Don't Know Jack", which will be telecast on Friday, 1 May, 8pm.

The official synopsis of the supernatural series hints that the detective might have no time to take care of his lady love, as he could be busy with a new case, which may lead the veterinarian to a darker path.

As the protagonist and his partner Hank Griffin (Russell Hornsby) investigate a string of homicides that created a fear that Jack the Ripper copycat has arrived in Portland, they also have to respond to an unexpected situation, states the description for the upcoming sequel.

Meanwhile, Adalind Schade (Claire Coffee) and Rosalee Calvert (Bree Turner) work together on a last-ditch attempt to fix Juliette's condition. But Tulloch's character will help her new ally, even if it means hurting those around her.

However, the title of the upcoming sequel hints that the veterinarian will turn out to be more dangerous than the Ripper as she is all set to take her revenge, putting her life in danger.

To know more about episode 20 titled "You Don't Know Jack", "Grimm" fans can tune in to NBC on Friday night, 1 May, 8pm