After finishing dinner, Simon is approached by beautiful, young and blonde Betty Connolly, who asks him for help. She'd been told who he was by Ziggy the cab driver. Although Betty had been born in Headstone her father had sent her out East to school many years ago, and she only returned a month ago, to attend his funeral. He left her only a played out silver mine, called the Betty Mine. But no one in town has been friendly towards her, a man named Mike McCarthy has told her to get out of town, and someone has actually taken shots at her! Yet the mine is supposed to be worthless. Simon agrees to help her, and decides to pay a visit to Harry Kelly, who had been the one friendly voice in the Headstone wilderness. As Simon gets up from his chair Betty brushes some red dust from his coat.

Simon and Betty get into Ziggy's cab, Simon complaining about the red dust in the back seat. ''So I had a red-headed passenger with dandruff,'' jokes the ex-New Yorker. He drives them to Harry Kelly's place, pointing out that he's a man who minds his own business. Simon tries to pump him, Betty asks him not to get Ziggy involved. Betty and Simon go up to Harry Allen's door while Ziggy waits for them in the cab. Simon knocks, but before Allen can open the door two shots are fired! Simon breaks down the door in time to hear Allen gasp with his dying breath: ''Mine...sin...sin..'' After finding an empty shell casingon the ground outside one of the windows, Simon says grimly, ''Come on, Betty, we're going to spread a little saintliness.''

''Didn't you see anything?'' Simon asks Ziggy as they head toward their next stop, Old Man Matthews, the town assayer. Ziggy denies all knowledge. He was minding his own business. Simon goes alone to Matthews' door, and is informed by the crotchety old man that the Betty Mine isn't worth anything.

After that,they go to visit Mike McCarthy, an Easterngangster who's been living in Headstone for a few months. Again Simon goes in to visit him alone. Simon accusses him of doing some shooting, the gangster denies it but pulls a revolver out of his pocket. Using subterfuge, Simon knocks him out and leaves.

Betty and Simon ditch Ziggy for Betty's own car, and she drives him out to her mine. Although the mine hasn't been worked in years it still has a working electrical system and a cable car system that goes down the full lenth of the mine, 354 feet, 6 inches. Simon and Betty start to get into the car when they are interrupted by Mike McCarthy, again with his gun. They're all three going down the mine shaft, only he will be coming back up. ''Unless that cable brakes,'' Simon comments, and as McCarthy looks up at the cable Simon calls him a sucker and knocks away his gun. They fight, and McCarthy falls out of the car to his death. Simon notices that in the struggle he got red dust on the padded shoulders of his coat.

On the way back to town, where they will exchange Betty's car for Ziggy's cab so Ziggy can drive him in to Albuquerque to catch a train (the Chief), Sinmon explains that the red dust on his coat was red sulphide, which is also cinnabar ore, which is where mercery comes from, and mercury is valuable, especially in war time.

As Ziggy drives them to Albuquerque, Betty happily tells Ziggy of her good fortune. They arrive in Albuquerque and Betty says, ''But how do I know the sheriff will believe me when I tell him Mike McCarthy shot Peters?''

''I don't think he will,'' says Simon, because actually it was Ziggy who shot Peters. McCarthy carried a revolver, which does not eject spent shells as an automatic does. Red dust in Ziggy's car gave him away, plus the fact that only Ziggy knew he and Betty were going to themine, yet McCarthy had been waiting for them. ''Why did he tell me to ask your help?'' ''He couldn't be sure that I wasn't here to break up his little scheme, so the smartest thing to do was to get us together,'' so he could keep tabs on them both. Ziggy pulls his automatic, the Saint knocks him out, and leaves Betty to call the Sheriff while he catches his train. ''Don't worry, Betty, I'll stop back some day to make sure that Venus is still in conjunction with Mercury.''

Vincent Price gives us an apropos quote at the end:
''Murder may pass unpunished for a time
but tardy justice will o'ertake the crime.''
John Dryden