Despite the title being 100% misleading, this is among Abbott and Costello's better films. No, Boris Karloff is NOT the killer and he is only a supporting character and so putting his name on the title (as was done in many cases) was deceptive and makes this appear to be a horror flick, while it's actually a murder mystery. I personally like this film because like some of their other better films (such as A&C Meet Frankenstein or A&C Meet Dr. Jeckyl and Mr. Hyde), the team does not rely on or fall back on worn-out old vaudeville routines but has plenty of action and excellent support. While I am not saying this is a perfect film, it does please and will appeal to both kids and adults.
