 His children's books present a gritty realism that children identify with, which provides a context for empathy and compassion for the underdog, and a desire for decency, justice and morality.They are often set in urban environments plagued by poverty and crime.Some are set in wartime, including his 24th full-length novel for young people, "Shadow of the Zeppelin" (2014), and his 25th, "Dead End Kids" (2015).