Set in the Thirty Years' war, Matchlock is the story of young Matthew Lock, a scion of a diplomatic family. The novel opens with a horrific scene of his older brother's murder before his eyes by villains in black masks. With a brief digression with the story of his adolescence at his parent's English estate, Lock is called to diplomatic service when his parents are murdered at their home in The Hague. We then set off on a series of adventures with at least one plot twist in every chapter. Early on Lock makes an improbable partnership with an Irish mercenary, which sets up an entire second set of plot twists within plot twists.This novel does a great job of portraying the devastation of the Thirty Years' War and its horrific impact upon the ordinary people of Germany.I think my favorite passage was the detailed description of Matthew Lock giving orders to a group of German fighters for the countermarch. Those of us who have read descriptions of the battles of Maurits van Oranje are familiar with the idea of the countermarch and know of its crucial role in the defeat of the Spanish tercios at the Battle of Nieuwpoort. But Twamley's breathtaking prose gives you the sense that you are watching the countermarch in action. For the first time, I understood why Spanish tercios were so vulnerable to it.Highly recommended.