If you want to get three of the Hot Dog Detectives in one volume, the trilogies are the way to go.
The first trilogy consists of Avid Angler, Busty Ballbreaker, and Crying Camper.
The second trilogy consists of Desperate Druggie, Eager Evangelist, and Freaky Fan
The third trilogy contains Groping Gardener, Harried Hairdresser, and Impetuous Intruder
The fourth trilogy has Jaded Jezebel, Kitchen Khemist, and Lazy Lawyer