***SPOILERS*** Private investigator Mike Barnett gets involved in a both murder and insurance scam in far off White Plains NY when he gives a life insurance agent Ann Stevens a ride in his car who found herself locked out of the Fuller property that's been vacant since the end of WWI.It turned out the person she was to meet the last surviving member of the Fuller family Charles Fuller disappeared and possibly got himself lost on the way there!
In the Fuller place both Barnett and Ann are surprised to discover the Fuller's Horace and Hortense who's been there unnoticed for the last 35 years with their creepy butler Dobson living in total obscurity to the world around them! As for Charles Fuller, the person that Ann was to meet, he was nowhere to be found and possibly lost in the woods! Smelling a rat in all this Barnett soon got the truth out of the "Fullers" by asking them, especially Hortense, trick questions that proved to him that they were not the brainless and innocent quacks that they made themselves out to be. And even farther more that Fuller the other third of the Fuller trio was in fact in the house dead and buried under a foot of concrete by Dobson to keep him quite!
***SPOILERS**** It was by accident that Barnett came on to this case in trying to help Ann clear up this Fuller mystery but he also ended up saving her as well as his life by turning the tables on the Fullers and their partner in crime Dobson who planned to murder them and pack them, with a foot of wet concrete, in the Fuller house basement. That by Barnett disarming a wild and crazed Dobson as well as getting the Fullers exposed as the on the lamb from the law-since 1919-fugitives that they really were as well as faking their deaths to escape justice for some 35 years since they went under the radar!