Oswald likes everyone to call him Drummah, as although he doesn't usually talk much, he has a feeling for rhythm that he often expresses by drumming on things. Fairly chill and happy to go along with things, his sole other passion is food, which may or may not be due to growing up homeless and not always being able to get it. He and his friends Gwenendale Griggs and later Tracy Starr stuck together as they worked to make ends meet. They eventually turned to music to do this, and Drummah and Gwen had to watch Tracy's and their backs when her passion for equality among the species came into their songs.
Story Summary (Spoilers Beyond This Point)
The HamstaPowah band are preparing for their last gig of the concert year. The show goes well, Drummah holding up to his namesake. However, during the performance a young mouse boy breaks into the building, on the run. After a little help from the band, the mouse slips and falls, but is caught by J'Aime Beck, HamstaPowah's number one fan who was helping with some of her friends backstage so they can watch the show. Tracy wants to help the boy, in spite of Mark Hamsta discovering a mark on his shoulder that indicates he's from a human lab, and Drummah sides with her, saying it's no big deal. Tracy adopts the mouse and names him Darin Starr, since he seems unable to speak.
After the show, the band are on their way back to their out of town residence, riding atop their cat Bobo, when a strange robotic machine attacks them. Bobo is stunned by an electrical attack and everyone else is sent flying, including Drummah, who misses most of what follows. The robot tries to capture Sarai Kerice, a young most who, along with her mother Kamilia Kerice, has been taken in by the band as paid workers after Sam freed them. Darin however intercepts it, demonstrating an odd power and fending it off briefly before being overcome. This buys time for Mark and Bobo to attack the robot, landing a lucky hit on its weak point that destroys it. Everyone else is intact, and they decide to quickly head on home.
Later on, while the band are doing errands in Crosond, the city is beset by an army of robots like the one they faced. Aside from Snowbell Crystal, they manage to keep out of the way this time, and Mark finds Darin, who was caught up in things again, so they take him back to their home to recover. Later still the band hears news of an explosion of unknown cause that has wiped out part of the red district of the city, causing them all to worry for their friends.
Sarai goes to check on Darin, and the others hear a mysterious thump. Snowy yells at Drummah to keep it down from the kitchen, but he pokes his head down to say it wasn't him and came from up on the roof. Everybody heads up there, and they find Darin standing in a strange symbol marked out in chalk, and are unable to stop Sarai stepping onto it, which causes them to vanish in a pillar of light that bursts from the symbol. Sarai is taken to a strange realm where she is shown Darin's memories, the others witnessing the same images projected on the pillar of light. They see the human scientist who claimed full responsibility for the attack, Darin's condition, and a plan to revert the non-human species, allowing them to piece together far more of the puzzle. Lastly, Darin appears lucidly, asking for their help stopping him, before passing out again in exhaustion. The day having been a surprising and eventful one, everyone turns in, considering what they've seen and getting some rest on it.