Early 18th-century Krakow: The poor student Simon works as a travelling musician in order to finance his studies, and the Polish freedom fighter Jan is on the run from Saxon troops. They meet in the carriage of Count Kovalska, where they fall in love with the Count’s daughters Laura and Bronislava.

When the Paris airport management is informed by telephone that there is a time bomb on board a Canadian Atlantic Airways plane to Montréal, they initially believe it is a bad joke. But the caller answers again. Inspector Bignon gets involved...