Two orphans, Polly and Doug, live with their stepmother Lynne; Polly collapses with the same mystery symptoms that killed her father. The kids’ visiting uncle, Whitney Cameron, is warned that the symptoms match strychnine poisoning, but that poisoners are seldom detected and rarely convicted. Sure enough, no case can be made against the obvious suspect; so what can Whitney do to save the next victim?
Michel Piccoli plays a police inspector whose best friend is murdered on the orders of gang boss Charles Vanel. The inspector knows full well that Vanel is too crafty and well-connected to ever stand trial for his crime, so he carefully lays a subtle trap for his adversary.
Following the narcotics-related death of her nephew, housewife and mother Phyllis Carter volunteers to work undercover for the police department to help apprehend drug runners. Though her offer is initially refused, Phyllis is eventually given the alias of Lynn Stuart, and assigned to insinuate herself into the life of criminal Willie Down. Becoming involved with Willie, Phyllis immerses herself further into her assumed identity and away from her domestic life.
Caddish lawyer Lee Gentry is going out with Katy Costello, but carrying on an affair with dancer Carmen Brown . When he wants to end the dalliance with Carmen, she is so distraught that she becomes suicidal. Seizing the gun from Carmen, he accidentally shoots her, and thinking she’s dead, concocts a series of increasingly outlandish alibis to cover his tracks under the guidance of a ghostly apparition that is his alter ego.
Richard Barrie is a outwardly charming young man who befriends Louisa and her two daughters, Florence and Eleanor. The family is vacationing in a resort town, next door to an unoccupied cottage. Richard sweet talks his way into renting the cottage, so that he may drop in on the family any time he likes. One of those times, he reveals himself to be a homicidal maniac.
A group of railroad workers decide to make extra money by smuggling forbidden goods and engaging in other criminal activities. Inspector is discovering gang members one by one. One of the thieves is losing his nerves because ongoing investigation and he’s being pushed in front of the train. After his murder, the whole case is getting different dimension, and the investigation is more effective. All clues are leading to the leader of the gang.
Sam Persson is released from a mental hospital. He goes to Stockholm to meet a man he hates, theater manager Stig Brender. In Brender’s office they get into a fight and Persson falls down dead. Brender uses his car to get rid of the body in a park. However, the following day he is visited by police inspector Envall, who wants to talk to him. Brender’s lies and strange behavior is no match for some thorough police work.
