The Broken Horseshoe (1973)

Based on the novel by Jules Verne "Drama in Livonia". French aeronaut Jules Ardan, traveling in a hot air balloon, accidentally finds himself in Reval. Here he meets Dr. Peterson and his daughter Leida. The gendarmes are hunting for Leida's fiance. The banker's son is being murdered in the city. Suspicion falls on Peterson. Jules Ardan takes over the investigation of the crime.