The year is 1875. The Arizona Territory is a wild, sparsely settled place. The Martin family's Box M Ranch is ten miles from their nearest neighbor and twenty miles from Tucson. Ma has been gone for two years, and Pa hasn't been the same since she passed. Something inside him broke when he lost her. Fifteen-year-old Ruth, fourteen-year-old Thad, twelve-year-old Sarah, ten-year-old Bart, and eight-year-old Billy have been doing most of the work to keep the Box M running. Consequently, when Pa passes away, the Martin siblings face little change in their daily routine as far as their chores go.

They do, however, face an ominous threat. Ruth, Thad, and Sarah know they can continue to run the Box M without Pa. They also know if folks discover Pa has passed away, the local lawman will load the Martin siblings into a buckboard and haul them off to the orphanage near Tucson. Ruth is confident she, Thad, and Sarah can protect their secret from the occasional travelers who visit the Box M, but she's concerned about Bart and Billy. They need to practice their conversations with each other to prepare for talking with strangers. They need to pray for God's help as they tackle a nearly impossible task. They need to work together. They need to become the Box M Gang.

During the next few months, visitors to the Box M include the sheriff, a bounty hunter, cattle rustlers, and a family with five small children. Some of the visitors stay long enough to rest and water their livestock. Some spend the night and move on the next day. Others overstay their welcome. All of them pose a threat to the Martins.

Can they keep their secret and remain on the Box M? Saddle up, and let's find out!