Despite an urgent warning from a friend, a man nicknamed the Swede passively waits for two hired gunmen sent to kill him. The Swede's death is investigated by Riordan, who works for the company that insured his life. The friend who worked with the Swede at a gas station tells Riordan that the Swede became withdrawn recently after running into a wealthy customer. The beneficiary of the Swede's insurance policy works as a maid at a hotel where the Swede had once stayed years ago. She prevented him from killing himself after he'd been distraught over a woman leaving him.
Intrigued, Riordan tracks down the Swede's real name, Ole Anderson, his childhood friend, Lieutenant Lubinsky, and his ex-girlfriend Lilly, the current Mrs. Lubinsky. In a series of flashbacks, Riordan pieces the Swede's story together. After an injury ended the Swede's boxing career, he fell in with the wrong crowd. Even worse for Lilly, he fell for Kitty Collins, girlfriend of thief Big Jim Colfax. The Swede was so obsessed by Kitty that he took the rap on some stolen jewelry for her. Even a jail term didn't diminish his obsession. After his release, the Swede and two men named Blinkie and Dum Dum agreed to take part in a payroll robbery planned by Colfax, Kitty's boyfriend. Colfax is also the wealthy customer who ran into the Swede at the gas station.
Lubinsky summons Riordan to hear the deathbed deliriums of Blinkie, who's just been shot. Blinkie lets loose that the Swede and Colfax fought over Kitty the night before the robbery. The Swede stole the payroll from the robbers after accusing them of trying to double cross him out of his share.
Riordan returns to the Swede's and finds Dum Dum tearing apart the Swede's place, looking for the payroll money. Dum Dum confesses to shooting Blinkie to prevent him from getting to the Swede's before he did. But he denies trying to double cross the Swede out of his share. He also denies killing the Swede because only the Swede knew where the money was. After a brief struggle, Dum Dum forces Riordan to tell him that Kitty was the one who walked out on the Swede and with the payroll. Dum Dum escapes.
Riordan visits Colfax, who denies knowing anything about the Swede or the payroll or Kitty's whereabouts. Riordan lies that he has proof connecting Kitty to the Swede after he stole the payroll from the robbers. Kitty meets with Riordan. She refuses to give up the entire payroll amount and Colfax, but she admits manipulating the Swede into stealing the payroll. She says she left him and used the money to get away from her hated boyfriend, Colfax.
Kitty escapes from Riordan. The same two gunmen who killed the Swede attack him, but they're shot dead by Lubinsky. Riordan, Lubinsky and the cops go to Colfax's house. They find Dum Dum shot dead, Colfax dying and Kitty outside. Colfax and Kitty turn out to be married. Colfax confesses that he and Kitty set up the Swede. Blinkie and Dum Dum thought that the Swede was acting on his own when he stole the payroll. If they had known about the Swede and Kitty, they would have gone after Kitty and Colfax, since they knew that the couple was married.
The Swede didn't know that Kitty had returned to Colfax after she left him and took the money. Colfax and Kitty had framed the Swede because they didn't want to split the take from the payroll robbery with their accomplices. Colfax says he had to have the Swede killed so that the Swede could never tell Blinkie or Dum Dum about his involvement with Kitty and to prevent the Swede from coming after him.
Kitty begs Colfax to tell the cops that she's innocent about the hired killers but he dies without lying for her.