The Night Master wants Coop to spy on the students to know what they are thinking. But when the Night Master hears what Yang thinks of him, he grows angry and shoots a beam out of the phone to hit Yin. Now the students know the Night Master has a spy. Yin and Yang use the Chronologicum to travel through the time stream to see if they can figure out who the spy is. However, the Chronologicum gets damaged, and Yin and Yang are separated in two different times.