The Stereo Brothers, A.M. and F.M., worked for music producer Flipside who was himself a member of the national criminal organization, the Apparatus. The twins did Flipside’s dirty work, approaching D.J.’s and others in the business and offering them payola (jewelry, cars, drugs, etc) in exchange for Flipside Inc. brand music to be played in their venues. If the approached individuals caused a problem, such as when Jake Staxx decided to turn states evidence, the two used a black sound box to silence the problem. The black sound box produced a silent black sound that triggered a heart attack in its victims. The Stereo Brothers approached D.J.’s Themesong and Garry Doll to get them to play Flipside music, the two refused and Garry put the fairly scrawny twins into a dumpster. The twins would return another night and kill Garry using their sound box. Having been identified by Themesong and a Janitor, the twins went to ground, but turned up in Flipside’s music studio to get his permission to kill Themesong. He granted permission, but Sparkle Plenty was in studio at the time and called it in to Dick Tracy. The twins hid in Themesong’s car and tried to use the black sound box on her, but Sam Catchem and Lizz Worthington arrived to save her and the twins fired on the two detectives. After a running gunfight, the Stereo Brothers, who had been wearing ear plugs to protect themselves from black sound, ran in front of a large truck and were crushed.