A young bunny grows into greater responsibilities when his little sister arrives. Already a big brother, he thinks he knows everything about younger siblings. But Sister seems to be much more trouble than he had imagined. Realizing that not all children are alike, he finds that watching Sister is much harder than it sounds. Even though this oldest child would love to abandon his babysitting duties, it seems Brother is always in charge of watching Sister. Whether it's a family outing at an amusement park or a trip to the store, all the grown ups tell him to "Stay with Sister." Whenever she slips away (as she tends to do) Brother is the one in trouble. He becomes frustrated, but eventually, as in his previous adventures with family bonding, he learns that having siblings who love you and look up to you isn't such a bad thing after all.