Norrmalmstorg robbery: Stockholm police secure the surrenders of hostage-takers Jan-Erik Olsson and Clark Olofsson, defusing the Norrmalmstorg hostage crisis. The behaviours of the hostages later give rise to the term Stockholm syndrome.

The Norrmalmstorg robbery was a bank robbery and hostage crisis that occurred at the Norrmalmstorg Square in Stockholm, Sweden, in August 1973 and was the first crime in Sweden to be covered by live television. It is best known as the origin of the term Stockholm syndrome.

Stockholm is the capital and most populous city of Sweden, as well as the largest urban area in the Nordic countries. Approximately 1 million people live in the municipality, with 1.6 million in the urban area, and 2.5 million in the metropolitan area. The city stretches across fourteen islands where Lake Mälaren flows into the Baltic Sea. Outside the city to the east, and along the coast, is the island chain of the Stockholm archipelago. The area has been settled since the Stone Age, in the 6th millennium BC, and was founded as a city in 1252 by Swedish statesman Birger Jarl. The city serves as the county seat of Stockholm County.

Jan-Erik "Janne" Olsson is a Swedish criminal, born and raised in Ekeby, outside Helsingborg. He was the main culprit in the 1973 Norrmalmstorg robbery in Stockholm, for which the term Stockholm syndrome was named.

Clark Oderth Olofsson was a Swedish criminal. He received sentences for attempted murder, assault, robbery and dealing narcotics and spent more than half of his life in prison. Olofsson was often referred to as Sweden's first "celebrity gangster".

Stockholm syndrome is a proposed condition or theory that tries to explain why hostages sometimes develop a psychological bond with their captors. Emotional bonds can possibly form between captors and captives, during intimate time together, but these are considered irrational by some in light of the danger or risk endured by the victims. Stockholm syndrome has never been included in the Diagnostic and Statistical Manual of Mental Disorders (DSM), the standard tool for diagnosis of psychiatric illnesses and disorders in the United States, mainly due to the lack of a consistent body of academic research and doubts about the legitimacy of the condition.