Young auto mechanic Dan Brady takes $20 from a cash register at work to go on a date with blonde femme fatale Vera Novak. Brady intends to put the money back before it is missed, but the garage's bookkeeper shows up earlier than scheduled. As Brady scrambles to cover evidence of his petty theft, he fast finds himself drawn into an ever worsening "quicksand" of crime.
The Los Angeles police know that Pete Ritchie has been bringing drugs into the city, but they can't pin a single piece of evidence on him. After many botched attempts to get at the crook, they resort to having cop Madeleine go undercover and seduce her way into Ritchie's circle. Before she can get anywhere, she's abducted by Johnny, a government agent posing as a thug. But Johnny and Madeleine have no idea they're on the same side of the law.
Madeleine's middle-class family cannot understand why she puts off marrying a respectable young man, as they know nothing about her long-term affair with a Frenchman.
Frank Bigelow is about to die, and he knows it. The accountant has been poisoned and has only 24 hours before the lethal concoction kills him. Determined to find out who his murderer is, Frank, with the help of his assistant and girlfriend, Paula, begins to trace back over his last steps. As he frantically tries to unravel the mystery behind his own impending demise, his sleuthing leads him to a group of crooked businessmen and another murder.
Jane, a housewife, is confronted during her daily chores by Dennis, her married lover with whom she has had a long affair. Dennis tells Jane that he has to break off their relationship. She threatens suicide, but when she picks up a shish kabob skewer, the two struggle and Dennis is stabbed in the chest and collapses. Jane hides the body in the house. Before she can leave, her brother-in-law arrives and tells her that he knows about the affair and that he has invited her husband, her lover, and his wife to her house that evening so that he can tell them about the affair.
Secret Service agents make a deal with a counterfeiting inmate to be released on early parole if he will help them recover some bogus moneymaking plates, but he plans to double-cross them.
Through a fluke circumstance, a ruthless woman stumbles across a suitcase filled with $60,000, and is determined to hold onto it even if it means murder.
When his mother eloped with an Italian opera singer, Louis Mazzini was cut off from her aristocratic family. After the family refuses to let her be buried in the family mausoleum, Louis avenges his mother's death by attempting to murder every family member who stands between himself and the family fortune. But when he finds himself torn between his longtime love and the widow of one of his victims, his plans go awry.
Prof. Millard pretends to be dead and helps Jeff King ferret out Vulcan, the evil traitor at the science academy. Donning his Rocket Man costume King goes from one hair raising rescue to the next in order to keep the newly invented Decimator out of the clutches of Vulcan and his minions.
Treasury Department officials recruit a florist (Raft) to lead them to a wanted criminal (Macready); but once he gets too close, he finds he's the hunted.
A war veteran suffering from amnesia, returns to Los Angeles from a San Francisco veterans hospital hoping to learn who he is and discovers his criminal past.