In Hemelsleutel, Digna Sinke introduces us to Lea, the protagonist of a potential feature film she is making. Lea is asked to document the energy transition in the port area of Amsterdam, dissecting local politics and interests. What starts out as a professional venture, soon turns into something much more personal, as a flood of memories and associations bubble up within Lea. Slowly though, Digna’s own memories and Lea’s story start to merge, and as the boundaries between them become increasingly unclear, the film unfurls from a place of fiction into a more reflective and reflexive documentary.