The state security service has found out about a plot against the GDR and Officer Alexander Berg (Fred Delmare) is assigned to investigate. When Berg goes undercover in disguise, he stumbles upon a mysterious operation called "Black Velvet." He learns that what seemed to be a relatively harmless case of car racketeering is actually something much more serious. Will his courage and cleverness be enough to solve the case and thwart an act of sabotage at the Leipzig Trade Fair?

Based on the crime novel Der scharlachrote Domino (The Scarlet Red Domino) by Fred Unger.