"Walter" (John Beal) returns home to his father's home ready to console him for losing all his money after the collapse of the Southern Valley Electrical Company. Surprisingly, though, he finds "John" (Douglass Dumbrille) in good spirits having seen the writing on the wall and sold his stock earlier. Disgusted that this will leave the other stockholders ruined, he heads to the home of his gal "Marian" (Linda Hayes) whose father "Ray" (H.B. Warner) is having to sell up to pay his $200,000 debt. This is where the eponymous PI (Ralph Bellamy) comes in. The young man engages him to buy up the estate secretly so that he can return it to him. The decent old man refuses to accept and when, shortly afterwards, "John" is found murdered the hunt for a killer is on. It's quite a complex little mystery this, with plenty of red herrings and just about everyone is a suspect - even the usually butter-wouldn't-melt Spring Byington as the distant cousin "Carlotta" - a woman who keeps a monkey that might have homicidal tendencies. It's quite quickly paced and entertaining enough with pistols, pens, bows and arrows before a dunking in a swimming pool and a rather lame ending. The star for me was probably his wily assistant "Nikki" (Margaret Lindsay) who has the best of the dialogue and though it's all pretty forgettable, it's an OK watch for an hour.