An older woman who owns a motel is robbed at gunpoint by a man wearing a trench coat, hat, and bandana covering his face. The woman won't tell him where she keeps her money, so he slugs her with the gun, searches a few boxes, but then leaves empty handed.
When the Highway Patrol arrive she says she recognizes the man as somebody who checked into the hotel the night before, Roger Taylor, from the clothing he was wearing. Taylor professes his innocence though he has no alibi, and he admits to having a trench coat and hat, but none are found in his room. He's a man on his way to Baltimore who owns a grocery store and has no money problems.
Dan Matthews asks him if he'd be willing to take a lie detector test. Taylor agrees because he has nothing to hide. He passes the test which is given over four hours asking a combination of mundane questions and questions applicable to the crime. Then the test is given to the hotel owner to see if she is either lying or has doubts about who she is accusing. She passes too. So Matthews is at an impasse. He has two people with test results that are at odds with one another. The owner believes she is accusing the right man. The accused at least believes he didn't do it. Or one or both of them are sociopaths! Complications ensue.
"Lie detectors", or polygraphs which are their true names, were never administered like this - With the subject holding their fingers in the air and only that one sensor being employed. That would be a unigraph, and not at all accurate.
Putting it center stage in the script was interesting though, and maybe put a chill through any bad guys watching that might really think that the police managed to put God in a box.