When Mickey and Gus arrive, they see three Bunny Children running away from Gremlin Markus. He explains that he found a stash of Power Sparks, but the Bunny Children ate them! He instructs Mickey to go after them, saying he'll know the Power Spark Kids when they run 'away' from Mickey instead of 'towards' him.
All Mickey has to do is spray either Paint or Thinner at the Kids. Strangely, the Thinner won't hurt them, but either substance will force the Children to "cough up" the Power Sparks. The Quest is completed when Mickey has collected all three Sparks. Sending the Bunny Kids to jail is entirely optional.
Oddly, the Quest is given when Mickey and Gus see the Bunny Children running away from Gremlin Markus, in other words 'before' they know what to do.