Nate the Great and the Fishy Prize

Nate the Great is about to enter his dog, Sludge, in the smartest pet contest. But when the prize disappears, it looks as if the contest will flop. It's a tough case for Nate and Sludge as they search for clues leading to the missing prize. In more ways than one, it's a very fishy business. Can Nate and Sludge find the prize in time?