The Detective O'Malley MEGAPACK®, by Walter MacHarg (epub/Kindle/pdf)$0.99
This volume collects 21 stories featuring Detective O'Malley from the pages of Collier’s. They date from 1930 through the early 1940s. William MacHarg's title character is a lot of fun and sure to appeal to fans of classic puzzle mysteries.
Of the series (which numbers about 80 stories), Mike Grost wrote: "The brief tales are heavily plot oriented. Some of them have mystery puzzle plots, in others the killer's identity is simply found through police work. O'Malley puts great emphasis on coming up with ingenious ideas to make the killer confess, or make a damaging admission of guilt; the stories contain numerous gimmicks of this type."