A man named Tim Templeton tells a story about his imaginative seven-year-old self and his parents, Ted and Janice. One day, Tim is surprised when an infant wearing a business suit arrives at his house in a taxi, and Ted and Janice refer to him as Tim's little brother. Tim is envious of the attention the day-old baby receives, and suspicious because of the infant's clothes and the strange behavior he exhibits around Tim, but his parents are oblivious. He soon finds that his new baby brother is no ordinary baby, he is actually a secret agent known as "the boss" who has come to Earth when he has learns that adults have taken a greater love to puppies than to human babies, and wants Tim's help to set things right.