The story takes place hundreds of years in the future, with humanity having extensively colonized surrounding space, including beyond the Solar System.

In order to defend from unknown threats beyond known space, a security company creates highly advanced robotic soldiers to patrol the border.

Green penned a positive of the book, calling it "a considerable feat of both imagination and storytelling", "a well-told tale, full of wonders thrown off casually like sparks from a sparkler", and "a treat for readers who like their science fiction loaded with intelligent scientific extrapolation".

praised the book, stating, "The interplay of the two main 'hunting' groups and the conniving and double-dealing of the operation's joint chiefs of staff, who are deadly rivals, made for gripping reading.

"[6] The critic David Pringle gave the book two stars, writing, "The ingenious plot poses questions about the nature of intelligence, but it's a pity the prose and characterization are so clunky.