A dashing but mysterious man saves a gambler from suicide, crashes the posh party of a prominent industrialist, falls in love with his daughter, and finds himself in a web of intrigue revolving around her blackmailing fiance and a gang of counterfeiters.

Resistance member is sent to infiltrate Nazi intelligence during WW2.

This romantic story turns on a stirring infatuation that takes hold of three young people under the influence of Simon, a Prague student. After the study year, 18 year-old Julio returns to his parental home, a little chateau on the Otava river. There he converges with his childhood friend Petr and the young boatman's daughter Klárka. Sharing her beguilement with Simon, who has quickly turned a tranquil summer atmosphere into a relationship drama, is Julio's cousin Rosa.