Arguably the best Abbott and Costello movie ever. (I prefered Hold That Ghost, myself.) The comedy is rampant throughout the entire movie. Abbott and Costello work as luggage handlers and get a package. Inside are the remains of Dracula and Frankenstein. Dracula and Frankenstein go on a rampage and the Wolfman comes up to scare them all. This i one of the few Abbot and Cosello comedies where the comedy doesn't become redundant in the middle. Bela Lugosi plays Dracula. Right there you can't go wrong.
There's more about this movie on my Parody of Horror Movies Page.