premise: The second season of Shadowhunters had 20 episodes that are 22 minutes in length.
hypothesis: Shadowhunters . In March 2016 , it was announced that the series had been renewed for a second season of 20 episodes , which premiered on January 2 , 2017 . In April 2017 , it was announced that the series had been renewed for a third season of 20 episodes .