A seemingly psychopathic killer strangles waitresses on Monday nights and leaves lipstick crosses on their foreheads. Jane Wyman plays a restaurant owner and Nancy Rennick is victim number four. “The Investigators” begin tracking down a mysterious killer who preys on waitresses, but not in time to prevent the death of another young girl employed by restaurant owner Elaine, played by guest star Jane Wyman. Russ Andrews befriends a shy young waitress, Marla Jensen (Nancy Rennick), at Elaine's, but she fails to fake him into her confidence, refuses protection, and turns up as the killer's next victim Andrews’ investigation then leads him to Walter Keeler (Peter Leeds), a fast-talking salesman who had been observed bothering Marla in the restaurant the night of her death. Keeler establishes a clear-cut alibi, however, putting a new light on the case.

A wealthy horse breeder dies in an avalanche set off by a construction company’s dynamite charges and “The Investigators” suspect that the estate owner's death was anything but accidental.

Maggie Peters finds herself romantically attracted by the insecure young heir to a factory fortune when she attempts to unravel the mysterious series of fires which break out in a New England industrial town.

Charity Kittridge reluctantly poses as a pigeon to catch a murder-for-insurance ring because she needs the money. When she rejects a strong man (Cal Bolder) as her pigeon "bridegroom," detective Steve Banks (James Philbrook) steps in to stage the fictitious union. This lays the groundwork for the murder ring to be exposed. When Charity is on the verge of being killed, co-investigator Russ Andrews prevents the plan from failing.

A man believed dead asks an insurance company to change his beneficiary. “Investigators” locks the door with an appropriately titled yarn, “The Dead End Man.” Henry Jones plays a man who gives up his hum-drum life of commuting on the 7:10 train and becomes a Bowery bum. His wife hunts him down when she gets word that he has changed beneficiaries on his insurance. Pat Carroll as Blossom is one of his six new beneficiaries.