'Sillage' tells the story of the river Zenne, constructed as a reflection of the river on itself. We follow its underground flow through Brussels. Together with the Zenne, the film ripples through the underworld of the city. By entering the tunnel that hides her deep underground from our capital, we also enter the deepest part of herself. Outside she reflects the sun, in the tunnel she reflects nothing. There is no light, only concrete surrounds her. What happens when we shine light on the Zenne in these dark tunnels? She reflects on her own dark sides and past. Good and bad memories come up. She questions the way they described her and how they treated her. It was polluted, broadened, deepened, covered over… but never tamed. She continued to intrigue. Both in the past and now. How does she herself see her future? By shedding light on the river, we also shed light on Brussels today. The city is still struggling with "problems". Is the city responding well to these issues or is it trying to hide them, just as it did with the river hundreds of years ago?