Every year when summer is approaching, marble season starts. The short documentary Play for Keeps features Sieme and Bence, two star marble players. They are in the third grade at the Thijsse School, on the Dutch island of Texel. Within the framework of a riveting duel of marbles, filmmaker Arnold van Bruggen highlights how the characters of these two boys influence their game. Sieme, for instance, is a more agile player with more bravura than Bence. Bence is a more serious marble player because he has fewer marbles. Together with their classmates, these boys are under the spell of the game. That is why the teacher has to be strict at times: any stray marble on the classroom floor will become new additions to her own marble collection. As Bence puts it, "At the start of the season, everybody has forgotten the rules a little bit." In Play for Keeps, the children discuss the seduction of the game and their emotions. Not everybody wants to "play for keeps." Most of them would rather "play for pretend," because the marbles are too pretty to lose.