Short and Diggums: Private Investigators is a private investigating service run by Holly Short and Mulch Diggums. It never really took off, but instead was more about minor operations or observations, like the one depicted in The Lost Colony. While Holly was time-travelling in the sixth book, Doodah Day joined the company. Later, when Holly Short re-joined the LEP's Kraken Watch division, Mulch and Doodah Day were the only fairies working there.
In this investigation, Holly and Mulch were staking out and trying to capture a fish smuggling pixie, Doodah Day. While Mulch guarded Day's "bolt hole", Holly got entangled in a life-threatening situation in which Day was operating a sidewalk-recycling machine seemingly attempting to kill Holly between the blades of the machine. After narrowly escaping, Holly tried to chase after the fleeing pixie, but, without a Neutrino 3000 (which were only assigned to the LEP), she could do nothing but radio Mulch and watch Day get away. Suddenly, Mulch tunnled out from underneath Day and proceeded to swallow all but his head, as dwarf spittle hardens, creating a tight covering.
Just then, Wing Commander Vinyáya appears with a small group behind her, asking Holly to release Day. Puzzled, Holly and Mulch believe that she is part of the LEP. She alludes that she is not and tells the investigative duo to get into the waiting limo. From there, they are driven to a parking garage and then taken through a secret hallogram rock. Inside the secret facility, called Section Eight, they find the Centaur Foaly. They explain that they are a secret branch of the LEP and that they need to recruit Mulch and Holly. Later on, they even ask Doodah Day to join for a limited time as they use him for an expert driver who fits the bill of a child-sized character to play the part of Minerva Paradizo's younger brother.
In The Time Paradox, while Holly was time-travelling, Doodah Day joined the private investigator company. Later, when Holly Short re-joined the LEP's Kraken Watch division, Mulch and Doodah Day were the only people working there.