Left reeling after her thoughtless mistake causes a terrible accident, 12-year-old Army Morand channels her grief to protect someone in need. Army feels like her life has been blown to bits due to the death of her beloved dog--a death that is her fault because she left chocolate cupcakes where he could eat them, and everyone knows that dogs shouldn't eat chocolate. Army can't seem to stop hiding from everything and everybody, including her best friend, JennaLouise. Surprisingly, it is Elsie Jenkins, a schoolmate Army has never been friends with before, and Madison, a little girl who has just moved in across the street, who pull Army out of the swirling sadness and back out into the world. Madison is five, and autistic. Army sees her climbing a tree unsupervised and slipping into a window. It's not safe! Madison's mom is overwhelmed caring for Madison and her twin baby brothers, and by losing the family and friends who helped out back home. It's a situation with no easy solutions, but Army is overcome with the need to help make things right and prevent another worst thing from happening.

She learns about Service with a Wag, an organization that trains service dogs, but the cost is astronomical. Fortunately, a solution comes from an unexpected source, but it also means that Army must open herself up to having a new dog.