Theodore's older brother, Jason, is strong, smart, and handsome everything a young mouse should be. It is hard to measure up to such an example, especially when their father obviously prefers Jason. However, when their father becomes deathly ill Jason is nowhere to be found. He has set out to find adventure and make his fortune. Theo must care for their father and he doesn't know what to do. He called for the doctor; he would do anything to make his father well. Yet, his father's only request crushes Theo. He asked him to find Jason, and bring him home. It is clear that his father will never rest easy without his favorite son.

Bitter, and a bit frightened, Theo is determined to do his father's bidding. He struggles to be free of his jealousy, and find his brother. No matter how dangerous the search becomes.