The opening image from William Butler Yeats' poem "The Second Coming" (1920) is of a falcon "turning in the widening gyre," no longer able to "hear the falconer." The poem contains some of literature's most famous lines, the narrator observing "Things fall apart; the centre cannot hold; / mere anarchy is loosed upon the world."

In C.J. Box's "Force of Nature," the ancient art of falconry with its "almost religious overtones" shapes the gripping plot and its literate themes. Wyoming game warden Joe Pickett and his friend Nate Romanowski must confront an incident in Nate's past, when he was in Central Asia as a member of a Special Forces unit, the Peregrines (named after one of the rarest birds in falconry). The squad's leader (their falconer) acted immorally and the consequences were globally dire. The leader is now hunting the men who witnessed his actions, widening his reach to include Joe and his family.

Like the relationship between falconer and falcon, trust and loyalty define Joe and Nate's complicated friendship, one that's pushed to the extreme in this book. Nate has trimmed "his life to the bone," living close to the land and far from the law, whereas Joe is a family man, "upright and burdened with ethics." The men share a profound sense of duty to the natural environment and to those who depend on its survival for theirs, a theme that runs through all the books in this outstanding wilderness noir series.