Preparations for, and actual crossing of, the Berlin wall in protest against nuclear testing in the East and West.
Greenpeace activists Gerd Leipold and John Sprange start a trip in the Greenpeace hot air balloon 'Trinity' and land in East Germany territory where they are arrested and detained.
The balloon is later taken into custody by the East German police. Gerd Leipold: "We set out from a secluded ports field in Wilmersdorf. Berlin was the only place in the world where we could protest against nuclear testing by four nuclear powers at the same time."