Peter Wittenbach, once an influential civil engineer, is now a lonely man, spending his retirement in a geriatric center. His sole interest is the construction site of a tunnel in the near vicinity. He observes it constantly and thus discovers a major constructional flaw. No one believes him, however, and his intrusive behavior proves to be his undoing. Although Peter feels offended, misunderstood and shunned, he manages to find a way of intervening in the daily activities again.