Series 9, episode 3
Episode details
Date aired 25 November 2015
Previous episode Gregory's Beard
Next episode Mole-Mapping

Threeism was the third episode of the ninth series of Peep Show. Mark tries to rekindle his relationship with April, but to his chagrin he finds out that she is already married, and he proceeds to sabotage it. Jeremy, Joe and Megan try out an open relationship (threeism) to address Joe's philandry