A mischievous mutt turned out to be a very good girl. Such a good girl, in fact, that she saved a life.

Ruby is an Australian shepherd and border collie mix. She turned up in a Rhode Island animal shelter as a pup. Five families looking for pets chose her. Each brought her back. Ruby was just too rambunctious.

“She was a total knucklehead,” says shelter volunteer and dog trainer Patricia Inman. “She jumped and bit her leash. She wouldn’t sit or lie down. She just never stopped moving.” Still, Ms. Inman loved Ruby. She intervened when others suggested putting Ruby down.

Enter state police Corporal Daniel O’Neil. He needed a search-and-rescue dog. He liked Ruby’s energy and intelligence. Ms. Inman vouched for the dog.

Ruby was trained as a police K-9 dog. (K-9 is a group of police officers who use dogs to help in their work. K-9 sounds like the word canine, which means related to dogs!)

Fast-forward to October 2017. A teenage boy got lost for 36 hours while hiking. A human search party failed to find him. But Ruby led Corporal O’Neil straight to the teen, who had tumbled into a ravine. The boy was unconscious and in grave medical condition. Corporal O’Neil’s radio and GPS were out of range. But Ruby’s barking drew authorities to the scene.

The surprising twist: When Corporal O’Neil went to the boy’s home to deliver the good news, Ms. Inman opened the door. She is the boy’s mother. She helped save Ruby. Later, Ruby helped save her son.

What a tale! People have even turned it into a movie.

“It’s a true underdog story,” says Corporal O’Neil. “It’s like divine intervention.”

Why? People love stories about heroes—even furry ones—because we are made to long for the ultimate hero, Jesus.