Greenpeace activists Gerd Leipold and John Sprange start a trip in the Greenpeace hot air balloon 'Trinity' in protest against nuclear testing in the East and West. They cross the Berlin wall and land in East Germany territory where they are arrested and detained for a while. The balloon was 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."