Several of Blackwood's books depict a theme similar to The Shakespeare Stealer.a boy set down in unfamiliar territory who must learn to fend for himself. In Wild Timothy, a boy who prefers books to outdoor life is lost in the woods and must survive for several weeks on his own. The high school senior in The Dying Sun, used to warmth and the crowded city life of the year 2050, must undertake a journey to the frozen state of Missouri where winter is a way of life. In Beyond the Door, the main character discovers a parallel world and is placed in a life-or-death situation.

Although Blackwood relies on survival as a plot device, his main characters are always well developed, and they learn more about themselves and their abilities by overcoming physical threats.