Rhubarb is about Siem and Winnie who come from broken-up families. When Siem's father Rik and Winnie's mother Tosca fall in love they suddenly get an entirely new family.  During the wedding preparations the tension between their parents increases, and Siem and Winnie fear a new separation. To avoid this they decide to make an instructional video for their parents with advice on how to create a good relationship. Working on the video makes Siem and Winnie form intimate ties.