O'Malley Detective Agency is a detective agency appearing in The Magic Nation Thing.
The agency is hosted in the two front rooms of a shabby, antique and run-down Victorian house. One is a fairly large parlor complete with high ceiling and a marble fireplace, holding desks and tables. The other room, which used to be a dining room, hosts cabinets and office equipment. As neither Dorcas, nor Tree has interest in housekeeping activities, the place is messy, neglected and full of dust. Dorcas and her daughter Abby live in the remaining rooms of the house.
Dorcas wishes that Abby chose the career of an investigator and take over the agency some day, including using her special powers in her work, but Abby is not interested in it.
After Dorcas remarries her husband, she moves out and resumes her previous work as a secretary, letting Tree Torrelli to take over the detective agency.