In Vražda v hotelu Excelsior, the interwar period homicide detective squad from Prague investigates the murder of a wealthy woman, Mrs Matoušová, which threatens the reputation of the eponymous luxury hotel popular with Prague’s elite. Even the retired police inspector Mrázek (František Filipovský), who works at the Excelsior as a hotel detective, is unable to help at first. Although the investigation inevitably uncovers the hotel staff’s scheming, Vacátko and his team unerringly follow the trail that leads them to the murderer…
In a suburban villa, a woman of means is murdered. Police Superintendent Zdychynec from the Prague Liben neighborhood reports the case to Police Councilman Vacátko, upon whose order an investigation is launched immediately. Zdychynec begins to suspect the wooer of his own daughter, a handsome dragoon named Rudi, of the crime. In Rudi's absence, Zdychynec searches his rented room in the apartment of the elegant Mrs Dragicová. All his findings - among others, sand left on Rudi's jackboots and a decent amount of money in his bedside table - convince the superintendent that he is following the right lead, especially when Rudi refuses to say where he was at the time of the murder.
In the morning twilight of Prague, the dead body of the safe-breaker Toufar is found floating on the river Vltava with a knife in his back. Police inspectors visit Toufar's lover, the prostitute Anna Kulatá (Jirina Bohdalová), nicknamed Umbrella, and it is apparent that the moment before she opened the door of her flat, someone fled through the window. Umbrella is summoned for examination to the head of the criminal police - Police Councilman Vacátko Jaroslav Marvan, but although shocked by the photograph of the dead man, she does not confess to anything. Before Toufar, Umbrella lived with the safe-breaker Penicka (Radoslav Brzobohatý), who loved her very much and made her quit her street trade. But when he was sentenced to three years' imprisonment, Umbrella began to live with the brute Toufar, who chased her to street again. In the case of the murder, Penicka is therefore the prime suspect.
The bridegroom Jan Kaspar is an officer in the Klement Gottwald's Nová Hut rolling-mill. After bidding farewell to his freedom, he accidentally takes a sip from the bottle of tetrachlore which he stores at home. He disregards the dizziness, but the next day, he faints in the factory and has a brain concussion. During her regular tests, doctor Dudková is shocked by a high percentage of residual nitrogen found in Kaspar's blood. Doctor Bohácek, with whom Dudková consults, thinks that it is a liver disease and informs the head physician Filip. The doctors know nothing about tetrachlore and are in the dark about the case. Despite that, they immediately start to fight for Kaspar's life and their struggle consequently affects their personal lives.
