Most keys are designed to lock things in or out. However, most keys aren't hidden away with hopes of never being found. Nevertheless, this specific key is discovered and brings to light a mystery that has been hidden by parents from their children.
Fear and panic fills this tale as the young Nums expose a key that brings danger to the lives of their loved ones. Attempts to save family and friends cause even more trouble, and it puts their own lives at risk. With everyone racing around the city trying to end this latest fiasco, one father unwittingly performs an act that could end the life of his own son.
Past actions return to haunt their future. The stakes are deadly and no one is safe.