The inspiration for the series The Vault was one of the most notorious and, to this day, not fully explained robberies in Slovenian history: the robbery of the SKB Bank safe deposit boxes in Ljubljana more than two decades ago. At the center of the story is security guard Sonja, who is found at the crime scene as the only person left behind after a daring bank vault heist and therefore becomes the prime suspect.
Episodes
Security guard Sonja wakes up locked in a robbed bank vault with a hole in her memory. Inspectors Deja and Jaka believe she is involved in the robbery. There is no sign of a break-in, and Sonja kept her criminal record secret when she got the job. Mayoral candidate Gabrijelčič is surprised by the news of the robbery in the middle of the campaign, bank director Alenka is under pressure from her clients, and Sotler from the insurance company tries to get information from the police. Sonja promised her son that she would return, but all she remembers is a sound that she cannot explain.
Test results reveal that Sonja was not under the influence of drugs on the night of the robbery, thereby eliminating a possible explanation for her memory lapse. When the media reports that the bank entrusted millions to the care of a former addict, social services show up at Sonja’s door, followed by the city’s most expensive lawyer. Detective Deja pressures Sonja despite a lack of clear evidence, while the prosecutor reminds her that she has previously lost a case based on a hunch. Insurance investigator Sotler discovers that the safe-deposit boxes were filled with undeclared cash, whereas a mayoral candidate claims—quite unconvincingly—that he had nothing in his box.
Sonja's partner Peter's argument with a journalist goes viral, and Sonja promises her son something she doesn't even believe in. Sonja's lab results turn the investigation upside down. The lab results showing the presence of illegal substances in her body turn the investigation upside down, and Inspector Deja realizes that there is a way to enter the bank unnoticed. Sotler discovers who was entering the vault without checking the records, and Sonja's lawyer goes too far in his investigation. In the middle of the campaign, Gabrijelčič is surprised by a journalist who no longer sticks to her agreement. Sonja recognizes the source of the sound that has stuck in her memory and must choose between the truth and her son.
Sonja reflects on Peter and tries to figure out what she overlooked about him. Before the police can declare her an accomplice, she begins searching for evidence on her own. Sotler helps Deja and Jaka reconstruct the motive behind the robbery. It turns out that the perpetrators did not take only money from the safes, but also a black folder for which some people are willing to kill. Deja blames Jaka for a mistake that cost them several days of the investigation. While she struggles with a corrupt system, he returns to the footage and notices a gesture he has seen somewhere before. Sonja discovers an address where she might find answers to her suspicions, and perhaps those who know what really happened.
After a long night, Sonja gets answers to her suspicions, but not the ones she had hoped for. Meanwhile, inspectors Deja and Jaka tighten the net around the robbers. They uncover new, crucial evidence and trace a mobile phone signal that always disappears in the same place. It becomes clear to them that the bank robbery has exposed an even more sinister form of criminal activity. In the end, Deja and Sonja are both faced with choices that will profoundly affect their personal and professional lives: Sonja must make a decision that will shape her future with Vid, while Deja faces the dilemma of how high a price she is willing to pay for justice.
