Ben has just returned from his family's holiday adventure in Papua New Guinea, a beautiful place in Oceania with a lot to enjoy from nature. He has returned to Oregon with a pet that he now calls Muri. Sometimes, Ben calls him Mysterious Muri because of his surprises now and then, and because of how fast he masters things. Muri is not just an ordinary rat; he is a powerful-toothed giant rat from Mount Bosavi in Papua New Guinea.