Dick Tracy (Ralph Byrd) is a master detective for the FBI in San Francisco. Among his enemies are the master criminal The Spider, who is determined to defeat him and get away with his crimes. His various crimes include destroying the Bay Bridge and stealing the plans for a top secret jet. The Spider's master stroke is to capture Tracy's brother Gordon (played by Richard Beach and Carleton Young) and turn him against his brother. To do this he has his henchman Dr. Moloch (John Picorri) perform an operation on him that makes him evil. Now secretly part of Spider Ring, The Spider's group of allies, Gordon Tracy and his brother Dick become enemies.