Tiergan and Liam once promised their mother that they would protect their younger half-brother, Keefe, with their lives. Their childish vow soon becomes reality, however, when Keefe's father is murdered and Keefe's rival brother, Slone, takes the throne, making a promise of his own: to kill Keefe before he reaches his twelfth birthday.

The brothers flee from the castle in the middle of the night with Bernt, the late king's middle son, unexpectedly joining them. Slone swiftly follows, forcing the fugitives to scatter across the country in an attempt to mislead their pursuers. Crossing deserts, working mines, hiding their identities, and plotting an elaborate coup, the boys struggle to keep Keefe alive and hidden. Unsure who they can trust and desperate for help, Tiergan, Liam, Bernt, and Keefe test the boundaries of loyalty to keep the promises they made when they were young.