In the first book of the Westmark Trilogy, Theo asks, "Even if the cause (of war) is good, what does it do to the people who stand against it? And the people who follow it?" The answer to those questions is The Kestrel. Using a panorama of characters, Alexander shows war from all perspectives: from the leaders,' from the bystanders,' and from the soldiers.' Alexander draws on his own experiences of World War II to give the reader (of any age) insight into the moral complexities of war.

The second book of the Westmark Trilogy, the adventures of Westmark continues in "The Kestrel". Theo is now traveling through Westmark to learn more about the country. He and Mickle, now known as Princess Augusta, are hoping to be married after he returns. But suddenly and without warning, Westmark is thrown into turmoil as the neighboring country of Regia has declared war on Westmark. Theo is once again forced into making a hard decision, will he stay in the sidelines or fight for his country? Eventually, he joins under the command of Florian and his people to fight a guerrilla war against the troops of Regia. As he sees brave and honorable men die one by one, Theo finds himself changing into a merciless commander and a stranger to himself...

The main character is once again Theo. When Westmark is attacked by neighboring Regia, Theo is forced with a dilemma. Should he serve his love (Mickle) or should he serve his country? Eventually, Theo is compelled to join fighting along with Florian's forces because of a memory of his cowardice at the battle of Nierkeeping in "Westmark." Fighting a guerrilla-style war under the command of Justin, Theo begins to be baptised by fire. He sees comrade after comrade killed. He becomes filled with hatred for the enemy army. Eventually, he is given command and becomes Colonel Kestrel, a semblance of Theo who commits unspeakable acts in the name of war.

Alexander studies the morals of war through his characters. The reader is forced to examine psychological aspects of war in Theo. War is also shown through a leader's eyes with the examinations of Mickle, Theo, Justin, and Florian. The devastating effect of war on the countryside is shown from following Sparrow and Weasel.

The Kestrel is a brilliant continuation of the series. The plot is magnificent, and it has so much depth. The characterizations are excellent, and the issues studied are compelling. The Westmark Trilogy is a great piece of young adult literature.