A US scientist defects to the USSR and builds a large dome to protect their leaders from retaliation, allowing a massive strike on the US. The dome is really a pod to launch them into space.
In the year 2050 a prisoner reads about the invention of a time machine and so breaks jail to return to the past to rub out the one witness to his crime. However, as he attempts to assault the man, he realizes that he has been rendered intangible like a ghost so as to be unable to effect any change in the course of events.
A young girl is friends with a tightrope walker past his prime. The man is killed in his last act, but his ghost returns to make his friend well again.