Emily O'Reilly and her best friend Olivia have a knack for solving mysteries. Emily has been busily training her new puppy Sherlock to be a Search and Rescue dog so that the two can lead search-and-rescue missions someday. So when Emily stumbles across an old photo of Olivia's adoption day---a fact that has never been revealed to Olivia---the two quickly decide to uncover the mysterious details surrounding Olivia's birth parents.
But the girls soon realize that they are in over their heads and find themselves with a real mystery to solve when Emily's stepmother disappears . . . will Emily find out the secret behind the disappearance? And will Olivia ever learn the truth about her adopted parents?