In this novel, after a boy and his father adopt a puppy, an adventure begins as the three of them learn to make friends, deal with bullies, and become a family.

Six-year-old Jeffrey Hennings is sad because his mother died not very long ago. Now it's just him and his dad, Richard, and it has been difficult for them.

One day, after Jeffrey has a fight with another boy at school, he and his dad are walking home when they encounter a small brown-and-black puppy. A cowboy is selling the dog, and Jeffrey and his dad adopt him and call him Doc Holliday. As he settles in, Doc makes friends with a squirrel named Penelope. But one day, after overhearing a conversation that makes him think Jeffrey and his dad don't actually love him, Doc decides to run away and find his birth family. Out on the streets, he encounters a world of trouble. Only time will tell if Jeffrey and his dad will be able to find Doc and let him know that he really is part of their family.