Val is led down to the waterfront where she is confronted by a group of thugs employed by Jake Bello, the night club owner who had been using her sister Arlene in his bond fencing scheme. While struggling with them she glimpses the body of Arlene in the rumble seat of her car.
Then ... Tony arrives in time to see her being dragged off to a waiting boat at a lumber yard. He bravely takes them on but fails to prevent her from being kidnapped.
... and Now, this is supposed to be in San Francisco but some of the location shots in the movie's developing story were filmed in the Terminal Island/San Pedro area of the Los Angeles Harbor. There were several lumber yards in San Pedro at that time and Citysleuth has concluded that the kidnap scene was filmed at one of them, the E.K. Wood Lumber Company. Formerly located at the foot of 14th Street (map), it's no longer there but the arrow points to the spot most likely used for the scene shown above.
... a vintage photo ... Here's a 1937 photo of the the E.K. Wood Lumber Company with a view of Terminal Island across the Main Channel.
Some time later the police find Jake Bello, done in by Arlene's mystery killer, floating in the water at one end of a cantilevered bridge, .
Then ... Another look at the bridge reveals it to be the San Pedro Bascule bridge that used to span, north to south, a section of the Turning Basin (map). Unlike the nearby Henry Ford bridge that doubled as the movie's Butchertown Bridge - a combination road and railway bridge, this one was rail only.
... a vintage photo ... the San Pedro Bridge is seen at the bottom of this north-facing image taken in 1948. Jake Bello's body was depicted as floating alongside the north end of the bridge, indicated by the arrow. The bridge was subsequently damaged in a collision by a passing ship in 1955 and demolished shortly afterwards.
The police arrive too late to prevent the boat from speeding off with Val held down in the back.