Watch Grimm Season 4 : You Don't Know Jack Full Episode Online for Free in HD @ br br Air Date : October 24th, 2014 br Season Number : 4 br Episode Number : 20 br Episode Name : You Don't Know Jack br Networks : NBC br Genres : Drama, Fantasy, Mystery br br Storyline: br The fourth season of the NBC American supernatural drama series Grimm was announced on March 19, 2014. It is set to consist of 22 episodes. The series, created by David Greenwalt, Jim Kouf and Stephen Carpenter, follows a descendant of the Grimm line, Nick Burkhardt, as he deals with being a cop, and trying not to expose his secret as a Grimm.