A secretary at an agricultural cooperative reports fifty thousand dollars missing from the cooperative's safe just before a big payout is to be made. Dan Matthews and company respond to the call. The secretary blames herself, saying she was so busy on this day as the farmers came and went that she closed the safe, but didn't lock it. She has every list that the Highway Patrol would need to do their investigation including farmers who had been to the cooperative that day, and those who came inside versus those who stayed outside.
But not all is as it appears. The secretary took the money herself and has it in her purse. At lunch, she meets her accomplice and gives him the money to put in a safe deposit box in another town for a year until the heat is off.
She planned carefully, but Matthews has been eliminating possible suspects all morning and thus turns back to the people who actually worked in the cooperative near the safe. And then "the hand of fate" makes everything clear. To find out what I mean, watch and find out.
In 1957, such a woman as the titular efficiency secretary could really not hope for anything more career wise than that of secretary, teacher, or nurse - Careers that involved serving men. Not an excuse but perhaps an explanation for why such a person would turn to crime. In 1957, fifty thousand dollars was worth about 600 thousand in 2024 - Not an amount that would have you fixed for life, by any means. So perhaps this secretary was more interested in the challenge than the cash. It appeared that way.